Measuring transducer of vibration-type with four curved measuring tubes

ABSTRACT

The measuring transducer comprises: a transducer housing, of which an inlet-side, housing end is formed by means of a flow divider including four flow openings spaced, and an outlet-side, formed by means of a flow divider including four flow openings spaced, from one another. A tube arrangement including four curved measuring tubes connected to the flow dividers for guiding flowing medium along flow paths connected in parallel. Each measuring tubes opens with an inlet-side, measuring tube end into one of the flow openings of the flow divider and with an outlet-side, measuring tube end into one the flow openings of the flow divider. The two flow dividers are embodied and arranged in the measuring transducer, so that the tube arrangement extends both between a first and a second of the measuring tubes and between a third and a fourth of the measuring tubes. An imaginary longitudinal-section plane, with respect to which the tube arrangement is mirror symmetric and perpendicular to the imaginary longitudinal-section plane, an imaginary longitudinal-section plane, with respect to which the tube arrangement likewise is mirror symmetric. An electromechanical exciter mechanism of the measuring transducer serves for producing and/or maintaining mechanical oscillations of the four measuring tubes.

CROSS-REFERENCES

This application is a nonprovisional application based on U.S.Provisional application 61/282,132, which was filed on Dec. 22, 2009,and based on U.S. Provisional application 61/344,561, which was filed onAug. 20, 2010; and priorities are also claimed of German application102009055069.0 filed on Dec. 21, 2009, and of German application102010039627.3 filed on Aug. 20, 2010.

FIELD OF THE INVENTION

The invention relates to a measuring transducer of vibration-type formeasuring a medium flowably guided in a pipeline, especially a gas,liquid, powder or other flowable material, especially for measuring adensity and/or a mass flow rate, especially also a mass flow integratedover a time interval, of a medium flowing in a pipeline, at least attimes, with a mass flow rate of more than 1000 t/h, especially more than1500 t/h. Additionally, the invention relates to an in-line measuringdevice including such a measuring transducer.

BACKGROUND OF THE INVENTION

Often used in process measurements, and automation, technology formeasuring physical parameters, such as e.g. the mass flow, the densityand/or the viscosity, of media, for instance, an aqueous liquid, a gas,a liquid-gas-mixture, a vapor, an oil, a paste, a slurry or anotherflowable material, flowing in pipelines are in-line measuring devices,which, by means of a measuring transducer of vibration-type, throughwhich medium flows, and a measuring, and operating, circuit connectedthereto, effect, in the medium, reaction forces, such as e.g. Coriolisforces corresponding with mass flow, inertial forces corresponding withdensity of the medium and/or frictional forces corresponding withviscosity of the medium, etc., and produce derived from these ameasurement signal representing the particular mass flow, viscosityand/or density of the medium. Such measuring transducers, especiallymeasuring transducers embodied as Coriolis, mass flow meters orCoriolis, mass flow/densimeters, are described at length and in detaile.g. in EP-A 1 001 254, EP-A 553 939, U.S. Pat. No. 4,793,191, US-A2002/0157479, US-A 2006/0150750, US-A 2007/0151368, U.S. Pat. No.5,370,002, U.S. Pat. No. 5,796,011, U.S. Pat. No. 6,308,580, U.S. Pat.No. 6,415,668, U.S. Pat. No. 6,711,958, U.S. Pat. No. 6,920,798, U.S.Pat. No. 7,134,347, U.S. Pat. No. 7,392,709, or WO-A 03/027616.

Each of the measuring transducers includes a transducer housing, ofwhich an inlet-side, first housing end is formed at least partially bymeans of a first flow divider having exactly two, mutually spaced,circularly cylindrical, or tapered or conical, flow openings and anoutlet-side, second housing end is formed at least partially by means ofa second flow divider having exactly two, mutually spaced, flowopenings. In the case of some of the measuring transducers illustratedin U.S. Pat. No. 5,796,011, U.S. Pat. No. 7,350,421, or US-A2007/0151368, the transducer housing comprises a rather thick walled,circularly cylindrical, tubular segment, which forms at least a middlesegment of the transducer housing.

For guiding the medium, in given cases, also an extremely hot, medium,which flows, at least at times, the measuring transducers include,furthermore, in each case, exactly two measuring tubes of metal,especially steel or titanium, which are connected such that the mediumcan flow in parallel and which are positioned within the transducerhousing and held oscillatably therein by means of the aforementionedflow dividers. A first of the, most often, equally constructed and,relative to one another, parallel extending, measuring tubes opens withan inlet-side, first, measuring tube end into a first flow opening ofthe inlet-side, first flow divider and with an outlet-side, secondmeasuring tube end into a first flow opening of the outlet-side, secondflow divider and a second of the measuring tubes opens with aninlet-side, first measuring tube end into a second flow opening of thefirst flow divider and with an outlet-side, second measuring tube endinto a second flow opening of the second flow divider. Each of the flowdividers includes additionally, in each case, a flange with a sealingsurface for fluid tight connecting of the measuring transducer totubular segments of the pipeline serving, respectively, for supplyingand removing medium to and from the measuring transducer.

For producing the above discussed reaction forces, the measuring tubesare caused to vibrate during operation, driven by an exciter mechanismserving for producing, or maintaining, as the case may be, mechanicaloscillations, especially bending oscillations, of the measuring tubes inthe so-called wanted mode. The oscillations in the wanted mode are, mostoften, especially in the case of application of the measuring transduceras a Coriolis, mass flow meter and/or densimeter, developed, at leastpartially, as lateral bending oscillations and, in the case of mediumflowing through the measuring tubes, as a result of therein inducedCoriolis forces, as additional, equal frequency oscillationssuperimposed in the so-called Coriolis mode. Accordingly, the—here mostoften electrodynamic—exciter mechanism is embodied in such a manner,that, therewith, the two measuring tubes are excitable in the wantedmode, at least partially, especially also predominantly, to oppositephase bending oscillations differentially—thus through introduction ofexciter forces acting simultaneously along a shared line of action,however, in opposed direction.

For registering vibrations, especially bending oscillations, of themeasuring tubes excited by means of the exciter mechanism and forproducing oscillation measurement signals representing vibrations, themeasuring transducers have, additionally, in each case, a, most often,likewise electrodynamic, sensor arrangement reacting to relativemovements of the measuring tubes. Typically, the sensor arrangement isformed by means of an inlet-side, oscillation sensor registeringoscillations of the measuring tubes differentially—thus only relativemovements of the measuring tubes—as well as by means of an outlet-side,oscillation sensor registering oscillations of the measuring tubesdifferentially. Each of the oscillation sensors, which are usuallyconstructed equally with one another, is formed by means of a permanentmagnet held on the first measuring tube and a cylindrical coil held onthe second measuring tube and permeated by the magnetic field of thepermanent magnet.

In operation, the above described tube arrangement formed by means ofthe two measuring tubes is excited by means of the electromechanicalexciter mechanism, at least at times, to execute mechanical oscillationsin the wanted mode at least one dominating, wanted, oscillationfrequency. Selected as oscillation frequency for the oscillations in thewanted mode is, in such case, usually a natural, instantaneous,resonance frequency of the tube arrangement, which, in turn, dependsessentially both on size, shape and material of the measuring tubes aswell as also on an instantaneous density of the medium; in given cases,this wanted oscillation frequency can also be influenced significantlyby an instantaneous viscosity of the medium. As a result of fluctuatingdensity of the medium being measured and/or as a result of media changeoccurring during operation, the wanted oscillation frequency duringoperation of the measuring transducer varies naturally, at least withina calibrated and, thus, predetermined, wanted frequency band, whichcorrespondingly has a predetermined lower, and a predetermined upper,limit frequency.

For defining a free, oscillatory length of the measuring tubes and,associated therewith, for adjusting the band of the wanted frequency,measuring transducers of the above described type include, additionally,most often, at least one inlet-side, coupling element, which is affixedto both measuring tubes and spaced from the two flow dividers, forforming inlet-side, oscillation nodes for opposite phase vibrations,especially bending oscillations, of both measuring tubes, as well as atleast one outlet-side, coupling element, which is affixed to bothmeasuring tubes and spaced both from the two flow dividers, as well asalso from the inlet-side, coupling element, for forming outlet-side,oscillation nodes for opposite phase vibrations, especially bendingoscillations, of the measuring tubes. In the case of curved measuringtubes, in such case, the length of a section of a deflection curve ofany of the measuring tubes extending between the inlet side and theoutlet-side coupling elements, consequently the length of an imaginarycenter line of the said measuring tube connecting the areal centers ofgravity of all imaginary cross sectional areas of the respectivemeasuring tube, corresponds to the free oscillatory length of themeasuring tubes. By means of the coupling elements, which thus belong tothe tube arrangement, additionally also an oscillation quality factor ofthe tube arrangement, as well as also the sensitivity of the measuringtransducer, in total, can be influenced, in a manner such that, for aminimum required sensitivity of the measuring transducer, at least oneminimum, free, oscillatory length is provided.

Development in the field of measuring transducers of vibration-type has,in the meantime, reached a level, wherein modern measuring transducersof the described type can, for a broad application spectrum of flowmeasurement technology, satisfy highest requirements as regardsprecision and reproducibility of the measurement results. Thus, suchmeasuring transducers are, in practice, applied for mass flow rates fromsome few l/h (gram per hour) up to some t/min (tons per minute), atpressures of up to 100 bar for liquids or even over 300 bar for gases.The accuracy of measurement achieved, in such case, lies usually atabout 99.9% of the actual value, or above, or at a measuring error ofabout 0.1%, wherein a lower limit of the guaranteed measurement rangecan lie quite easily at about 1% of the measurement range end value. Dueto the high bandwidth of their opportunities for use, industrial grademeasuring transducers of vibration-type are available with nominaldiameters (corresponding to the caliber of the pipeline to be connectedto the measuring transducer, or to the caliber of the measuringtransducer measured at the connecting flange), which lie in a nominaldiameter range between 1 mm and 250 mm and at maximum nominal mass flowrate of 1000 t/h, in each case, for pressure losses of less than 3 bar.A caliber of the measuring tubes lies, in such case, for instance, in arange between 80 mm and 100 mm.

In spite of the fact that, in the meantime, measuring transducers foruse in pipelines with very high mass flow rates and, associatedtherewith, very large calibers of far beyond 100 mm have becomeavailable, there is still considerable interest in obtaining measuringtransducers of high precision and low pressure loss also for yet largerpipeline calibers, about 300 mm or more, or mass flow rates of 1500 t/hor more, for instance for applications in the petrochemical industry orin the field of transport and transfer of petroleum, natural gas, fuels,etc. This leads, in the case of correspondingly scaled enlarging of thealready established measuring transducer designs known from the state ofthe art, especially from EP-A 1 001 254, EP-A 553 939, U.S. Pat. No.4,793,191, US-A 2002/0157479, US-A 2007/0151368, U.S. Pat. No.5,370,002, U.S. Pat. No. 5,796,011, U.S. Pat. No. 6,308,580, U.S. Pat.No. 6,711,958, U.S. Pat. No. 7,134,347, U.S. Pat. No. 7,350,421, or WO-A03/027616, to the fact that the geometric dimensions would beexorbitantly large, especially the installed length corresponding to adistance between the sealing surfaces of both flanges and, in the caseof curved measuring tubes, a maximum lateral extension of the measuringtransducer, especially dimensions for the desired oscillationcharacteristics, the required load bearing ability, as well as themaximum allowed pressure loss. Along with that, also the empty mass ofthe measuring transducer increases unavoidably, with conventionalmeasuring transducers of large nominal diameter already having an emptymass of about 400 kg. Investigations, which have been carried out formeasuring transducers with two bent measuring tubes, constructed, forinstance, according to U.S. Pat. No. 7,350,421 or U.S. Pat. No.5,796,011, as regards their to-scale enlargement to still greaternominal diameters, have, for example, shown that, for nominal diametersof more than 300 mm, the empty mass of a to-scale enlarged, conventionalmeasuring transducer would lie far above 500 kg, accompanied by aninstalled length of more than 3000 mm and a maximum lateral extension ofmore than 1000 mm. As a result, it can be said that industrial grade,mass producible, measuring transducers of conventional design andmaterials with nominal diameters far above 300 mm cannot be expected inthe foreseeable future both for reasons of technical implementability,as well as also due to economic considerations.

SUMMARY OF THE INVENTION

Proceeding from the above recounted state of the art, it is consequentlyan object of the invention to provide a measuring transducer of highsensitivity and high oscillation quality factor, which also in the caseof large mass flow rates of more than 1000 t/h, causes only a smallpressure loss of, as much as possible, less than 3 bar and which alsoshows a construction, which is as compact as possible at large nominaldiameters of over 100 mm and, not last, is also suitable forapplications involving extremely hot, or extremely cold, media and/orsignificant fluctuating media temperatures.

For achieving the object, the invention resides in a measuringtransducer of vibration-type for registering at least one physical,measured variable of a flowable medium guided in a pipeline, forexample, a gas, a liquid, a powder or other flowable material, and/orfor producing Coriolis forces serving for registering a mass flow rateof a flowable medium guided in a pipeline, especially a gas, a liquid, apowder or other flowable material. The measuring transducer comprises,according to the invention, a, for example, essentially tubular and/orexternally circularly cylindrical, transducer housing, of which aninlet-side, first housing end is formed by means of an inlet-side, firstflow divider including, especially exactly, four, for example,circularly cylindrical, tapered or conical, flow openings spaced, ineach case, from one another, and an outlet-side, second housing end isformed by means of an outlet-side, second flow divider including,especially exactly, four, for example, circularly cylindrical, taperedor conical, flow openings spaced, in each case, from one another.Furthermore, the measuring transducer comprises a tube arrangement withexactly four, straight measuring tubes forming flow paths arranged forparallel flow and connected to the, for example, equally constructed,flow dividers for guiding flowing medium, especially measuring tubesheld oscillatably in the transducer housing only by means of said flowdividers and/or equally constructed and/or pairwise parallel relative toone another, and bent, for example, at least sectionally V-shaped or atleast sectionally circular arc shaped. Of the four measuring tubes, forexample, measuring tubes constructed equally both as regards geometry aswell as also as regards material, a first measuring tube, especially acircularly cylindrical, first measuring tube, opens with an inlet-side,first measuring tube end into a first flow opening of the first flowdivider and with an outlet-side, second measuring tube end into a firstflow opening of the second flow divider, a second measuring tube, whichis at least sectionally parallel to the first measuring tube, opens withan inlet-side, first measuring tube end into a second flow opening ofthe first flow divider and with an outlet-side, second measuring tubeend into a second flow opening of the second flow divider, a thirdmeasuring tube opens with an inlet-side, first measuring tube end into athird flow opening of the first flow divider and with an outlet-side,second measuring tube end into a third flow opening of the second flowdivider, as well as a fourth measuring tube, which is at leastsectionally parallel to the third measuring tube, opens with aninlet-side, first measuring tube end into a fourth flow opening of thefirst flow divider and with an outlet-side, second measuring tube endinto a fourth flow opening of the second flow divider. Additionally, themeasuring transducer comprises an electromechanical exciter mechanism,for example, one formed by means of an electrodynamic oscillationexciter, for producing and/or maintaining mechanical oscillations,especially bending oscillations, of the four measuring tubes. In thecase of the measuring transducer of the invention, the measuring tubesare so embodied and arranged in the measuring transducer, that the tubearrangement shows lying between the first imaginary longitudinal sectionplane and the second imaginary longitudinal section plane of themeasuring transducer, and parallel to the first imaginary longitudinalsection plane of the measuring transducer and to the second imaginarylongitudinal section plane of the measuring transducer, a firstimaginary longitudinal section plane, with respect to which the tubearrangement is mirror symmetric, and the tube arrangement showsperpendicular to its imaginary first longitudinal section plane a secondimaginary longitudinal section plane, with respect to which the tubearrangement is likewise mirror symmetric.

According to a first embodiment of the invention, it is additionallyprovided, that the two flow dividers are additionally so embodied andarranged in the measuring transducer, that an imaginary first connectingaxis of the measuring transducer imaginarily connecting the first flowopening of the first flow divider with the first flow opening of thesecond flow divider extends parallel to an imaginary second connectingaxis of the measuring transducer imaginarily connecting the second flowopening of the first flow divider with the second flow opening of thesecond flow divider, that an imaginary third connecting axis of themeasuring transducer imaginarily connecting the third flow opening ofthe first flow divider with the third flow opening of the second flowdivider extends parallel to an imaginary fourth connecting axis of themeasuring transducer imaginarily connecting the fourth flow opening ofthe first flow divider with the fourth flow opening of the second flowdivider. Developing this embodiment of the invention further, it isadditionally provided, that a first imaginary longitudinal section planeof the measuring transducer, within which the first imaginary connectingaxis and the second imaginary connecting axis extend, for example,parallel to a principal flow axis of the measuring transducer aligningwith the pipeline is parallel to a second imaginary longitudinal sectionplane of the measuring transducer, within which the imaginary thirdconnecting axis and the imaginary fourth connecting axis extend, forexample, in such a manner, that the first imaginary longitudinal sectionplane of the tube arrangement lies between the first and secondimaginary longitudinal section planes of the measuring transducer and/oris parallel to the first and second imaginary longitudinal sectionplanes of the measuring transducer.

According to a second embodiment of the invention, it is additionallyprovided, that the two flow dividers are so embodied and arranged in themeasuring transducer, that a third imaginary longitudinal section planeof the measuring transducer, within which the imaginary first connectingaxis and the imaginary third connecting axis extend, is parallel to afourth imaginary longitudinal section plane of the measuring transducer,within which the imaginary second connecting axis and the imaginaryfourth connecting axis extend. Developing this embodiment of theinvention further, it is additionally provided, that the secondimaginary longitudinal section plane of the tube arrangement extendsbetween the third imaginary longitudinal section plane of the measuringtransducer and the fourth imaginary longitudinal section plane of themeasuring transducer, for example, in such a manner, that the secondimaginary longitudinal section plane of the tube arrangement is parallelto the third imaginary longitudinal section plane of the measuringtransducer and parallel to the fourth imaginary longitudinal sectionplane of the measuring transducer.

According to a third embodiment of the invention, it is additionallyprovided, that the four flow openings of the first flow divider are soarranged, that imaginary areal centers of gravity associated with crosssectional areas, especially circularly shaped, cross sectional areas, ofthe flow openings of the first flow divider form the vertices of animaginary rectangle or of an imaginary square, wherein said crosssectional areas lie in a shared imaginary cross sectional cutting planeof the first flow divider, for example, perpendicular to the firstimaginary longitudinal section plane of the measuring transducer, or tothe second imaginary longitudinal section plane of the measuringtransducer.

According to a forth embodiment of the invention, it is additionallyprovided, that the four flow openings of the second flow divider so arearranged, that imaginary areal centers of gravity associated with crosssectional areas of the flow openings of the second flow divider form thevertices of an imaginary rectangle or of an imaginary square, whereinsaid cross sectional areas lie in a shared imaginary cross sectionalcutting plane of the second flow divider, for example, perpendicular tothe first imaginary longitudinal section plane of the measuringtransducer, or to the second imaginary longitudinal section plane of themeasuring transducer.

According to a fifth embodiment of the invention, it is additionallyprovided, that each of the four measuring tubes, especially measuringtubes of equal caliber and/or equal length, shows a caliber, whichamounts to more than 40 mm, especially more than 60 mm. Developing thisembodiment of the invention further, it is additionally provided, thatthe measuring tubes are so bent and so arranged, that a caliber toheight ratio of the tube arrangement, defined by a ratio of the caliberof the first measuring tube to a maximal lateral expanse of the tubearrangement, measured from a peak of the first measuring tube to a peakof the third measuring tube, amounts to more than 0.1, especially morethan 0.2 and/or less than 0.35.

According to a sixth embodiment of the invention, it is additionallyprovided, that the first flow divider includes a flange, especially aflange showing mass of more than 50 kg, for connecting the measuringtransducer to a tubular segment of the pipeline serving for supplyingmedium to the measuring transducer and the second flow divider includesa flange, especially a flange showing a mass of more than 50 kg, forconnecting the measuring transducer to a segment of the pipeline servingfor removing medium from the measuring transducer. Developing thisembodiment of the invention further, each of the flanges includes asealing surface for fluid tight connecting of the measuring transducerwith the, in each case, corresponding tubular segment of the pipeline,wherein a distance between the sealing surfaces of both flanges definesan installed length of the measuring transducer, especially an installedlength amounting to more than 1000 mm and/or less than 3000 mm.Especially, the measuring transducer is additionally so embodied, that,in such case, a measuring tube length of the first measuring tubecorresponding to a length of a section of the deflection curve of thefirst measuring tube extending between the first flow opening of thefirst flow divider and the first flow opening of the second flow divideris so selected, that a measuring tube length to installed length ratioof the measuring transducer, as defined by a ratio of the measuring tubelength of the first measuring tube to the installed length of themeasuring transducer, amounts to more than 0.7, especially more than 0.8and/or less than 0.95, and/or that a caliber to installed length ratioof the measuring transducer, as defined by a ratio of a caliber of thefirst measuring tube to the installed length of the measuringtransducer, amounts to more than 0.02, especially more than 0.05 and/orless than 0.09. Alternatively thereto or in supplementation thereof, themeasuring transducer is so embodied, that a nominal diameter toinstalled length ratio of the measuring transducer, as defined by aratio of the nominal diameter of the measuring transducer to theinstalled length of the measuring transducer, is smaller than 0.3,especially smaller than 0.2 and/or greater than 0.1, wherein the nominaldiameter corresponds to a caliber of the pipeline, in whose course themeasuring transducer is to be used.

In a seventh embodiment of the invention, it is additionally provided,that a measuring tube length of the first measuring tube correspondingto a length of a section of the deflection curve of the first measuringtube extending between the first flow opening of the first flow dividerand the first flow opening of the second flow divider amounts to morethan 1000 mm, especially more than 1200 mm and/or less than 2000 mm.

In an eighth embodiment of the invention, it is additionally provided,that each of the four measuring tubes, especially four measuring tubesof equal caliber, is so arranged, that a smallest lateral separation ofeach of the four measuring tubes, especially measuring tubes of equallength, from a housing side wall of the transducer housing is, in eachcase, greater than zero, especially greater than 3 mm and/or greaterthan twice a respective tube wall thickness; and/or that a smallestlateral separation between two neighboring measuring tubes amounts to,in each case, greater than 3 mm and/or greater than the sum of theirrespective tube wall thicknesses.

In a ninth embodiment of the invention, it is additionally provided,that each of the flow openings is so arranged, that a smallest lateralseparation of each of the flow openings from a housing side wall of thetransducer housing amounts, in each case, to greater than zero,especially greater than 3 mm and/or greater than twice a smallest tubewall thickness of the measuring tubes; and/or that a smallest lateralseparation between the flow openings amounts to greater than 3 mm and/orgreater than twice a smallest tube wall thickness of the measuringtubes.

According to a tenth embodiment of the invention, it is additionallyprovided, that the exciter mechanism is embodied in such a manner, thatthe first measuring tube and the second measuring tube are excitableduring operation to opposite phase bending oscillations and the thirdmeasuring tube and the fourth measuring tube are excitable duringoperation to opposite phase bending oscillations.

In a eleventh embodiment of the invention, it is additionally provided,that a mass ratio of an empty mass of the total measuring transducer toan empty mass of the first measuring tube is greater than 10, especiallygreater than 15 and smaller than 25.

In a twelfth embodiment of the invention, it is additionally provided,that an empty mass, M₁₈, of the first measuring tube, especially each ofthe measuring tubes, is greater than 20 kg, especially greater than 30kg and/or smaller than 50 kg.

According to an thirteenth embodiment of the invention, it isadditionally provided, that an empty mass of the measuring transducer isgreater than 200 kg, especially greater than 300 kg.

In a fourteenth embodiment of the invention, it is additionallyprovided, that a nominal diameter of the measuring transducer, whichcorresponds to a caliber of the pipeline, in whose course the measuringtransducer is to be used, amounts to more than 100 mm, especiallygreater than 300 mm. In advantageous manner, the measuring transducer isadditionally so embodied, that a mass to nominal diameter ratio of themeasuring transducer, as defined by a ratio of the empty mass of themeasuring transducer to the nominal diameter of the measuringtransducer, is smaller than 2 kg/mm, especially smaller than 1 kg/mmand/or greater than 0.5 kg/mm.

In a fifteenth embodiment of the invention, it is additionally provided,that the first and the second measuring tubes are of equal construction,at least as regards a material, of which their tube walls are, in eachcase, composed, and/or as regards their geometrical tube dimensions,especially a tube length, a tube wall thickness, a tube outer diameterand/or a caliber.

According to a sixteenth embodiment of the invention, it is additionallyprovided, that the third and fourth measuring tubes are of equalconstruction, at least as regards a material, of which their tube wallsare, in each case, composed, and/or as regards their geometric tubedimensions, especially a tube length, a tube wall thickness, a tubeouter diameter and/or a caliber.

According to a seventeenth embodiment of the invention, it isadditionally provided, that the four measuring tubes are of equalconstruction, as regards a material, of which their tube walls arecomposed, and/or as regards their geometric tube dimensions, especiallya tube length, a tube wall thickness, a tube outer diameter and/or acaliber. It can, however, also be of advantage, when, alternativelythereto, both the third measuring tube as well as also the fourthmeasuring tube are different from the first measuring tube and from thesecond measuring tube as regards their respective geometric tubedimensions, especially a tube length, a tube wall thickness, a tubeouter diameter and/or a caliber.

In a eighteenth embodiment of the invention, it is additionallyprovided, that a material, of which the tube walls of the four measuringtubes are at least partially composed, is titanium and/or zirconiumand/or duplex steel and/or super duplex steel.

In a nineteenth embodiment of the invention, it is additionallyprovided, that the transducer housing, the flow dividers and tube wallsof the measuring tubes are, in each case, composed of steel, forexample, stainless steel.

In a twentieth embodiment of the invention, it is additionally provided,that the minimum bending oscillation, resonance frequencies at least ofthe first and second measuring tubes are essentially equal and theminimum bending oscillation, resonance frequencies at least of the thirdand fourth measuring tubes are essentially equal. In such case, theminimum bending oscillation, resonance frequencies of all four measuringtubes can be essentially equal or, however, also kept only pairwiseequal.

According to a twenty-first embodiment of the invention, it isadditionally provided, that the exciter mechanism is formed by means ofa first oscillation exciter, especially an electrodynamic, firstoscillation exciter and/or a first oscillation exciter differentiallyexciting oscillations of the first measuring tube relative to the secondmeasuring tube. Especially, the exciter mechanism is formed by means ofa second oscillation exciter, for example, an electrodynamic secondoscillation exciter and/or a second oscillation exciter differentiallyexciting oscillations of the third measuring tube relative to the fourthmeasuring tube. In such case, it is additionally provided, that thefirst and second oscillation exciters are interconnected electrically inseries, in such a manner, that a combined driver signal excites combinedoscillations of the first and third measuring tubes relative to thesecond and fourth measuring tube. The oscillation exciter of the excitermechanism can be formed, for example, by means of a permanent magnetheld on the first measuring tube and a cylindrical coil permeated by themagnetic field of the permanent magnet and held on the second measuringtube, and wherein the second oscillation exciter is formed by means of apermanent magnet held on the third measuring tube and a cylindrical coilpermeated by the magnetic field of the permanent magnet and held on thefourth measuring tube.

In a twenty-second embodiment of the invention, it is additionallyprovided, that a middle segment of the transducer housing is formed bymeans of a straight tube, for example, a circularly cylindrical,straight tube.

In a twenty-third embodiment of the invention, it is additionallyprovided, that the transducer housing is essentially tubularly embodied,for example, circularly cylindrically embodied. In such case, it isadditionally provided, that the transducer housing shows a largesthousing inner diameter, which is greater than 150 mm, especially greaterthan 250 mm, especially in such a manner, that a housing to measuringtube inner diameter ratio of the measuring transducer, as defined by aratio of the largest housing inner diameter to a caliber of the firstmeasuring tube is kept greater than 3, especially greater than 4 and/orsmaller than 5, and/or that a housing inner diameter to nominal diameterratio of the measuring transducer, as defined by a ratio of the largesthousing inner diameter to the nominal diameter of the measuringtransducer is smaller than 1.5, especially smaller than 1.2 and/orgreater than 0.9, wherein the nominal diameter corresponds to a caliberof the pipeline, in whose course the measuring transducer is to be used.The housing inner diameter to nominal diameter ratio of the measuringtransducer can, in such case, in advantageous manner, be, for example,also equal to one.

In a first further development of the invention, the measuringtransducer additionally comprises a first coupling element of firsttype, especially a plate-shaped first coupling element of first type,which is affixed at least to the first measuring tube and to the secondmeasuring tube and spaced on the inlet side both from the first flowdivider as well as also from the second flow divider for forminginlet-side, oscillation nodes at least for vibrations, especiallybending oscillations, of the first measuring tube and for theretoopposite phase vibrations, especially bending oscillations, of thesecond measuring tube, as well as a second coupling element of firsttype, especially a plate-shaped second coupling element of first typeand/or a second coupling element constructed equally to the firstcoupling element and/or a second coupling element parallel to the firstcoupling element, which second coupling element of first type is affixedat least to the first measuring tube and to the second measuring tubeand spaced on the outlet side both from the first flow divider as wellas also from the second flow divider, as well as also from the firstcoupling element, for forming outlet-side, oscillation nodes at leastfor vibrations, especially bending oscillations, of the first measuringtube and for thereto opposite phase vibrations, especially bendingoscillations, of the second measuring tube.

In a first embodiment of the first further development of the invention,it is additionally provided, that all four measuring tubes are connectedwith one another mechanically by means of the first coupling element offirst type as well as by means of the second coupling element of firsttype.

In a second embodiment of the first further development of theinvention, it is additionally provided, that the first coupling elementof first type is plate shaped, especially in such a manner, that itshows essentially a rectangular, square, round, cross shaped or H-shapedbasic shape.

In a third embodiment of the first further development of the invention,it is additionally provided, that the second coupling element of firsttype, especially a coupling element of construction equal to that of thefirst coupling element of first type, is plate shaped, especially insuch a manner, that it shows a rectangular, square, round, cross shapedor H-shaped basic shape.

In a fourth embodiment of the first further development of theinvention, it is additionally provided, that the first coupling elementof first type is affixed also to the third measuring tube and to thefourth measuring tube, and that the second coupling element of firsttype is affixed to the third measuring tube and to the fourth measuringtube.

In a fifth embodiment of the first further development of the invention,it is additionally provided, that a center of mass of the first couplingelement of first type shows a distance to a center of mass of themeasuring transducer, which is essentially equal to a distance of acenter of mass of the second coupling element of first type to saidcenter of mass of the measuring transducer.

In a sixth embodiment of the first further development of the invention,the measuring transducer is additionally so embodied, that a free,oscillatory length of the first measuring tube, especially of each ofthe measuring tubes, corresponding to a length of the section of thedeflection curve extending between the first coupling element of firsttype and the second coupling element of first type, amounts to less than3000 mm, especially less than 2500 mm and/or more than 800 mm.Especially, the measuring transducer is, in such case, additionally soembodied, that each of the four measuring tubes, especially measuringtubes of equal caliber and/or equal length, shows a caliber, whichamounts to more than 40 mm, especially more than 60 mm, especially insuch a manner, that a caliber to oscillatory length ratio of themeasuring transducer, as defined by a ratio of a caliber of the firstmeasuring tube to the free, oscillatory length of the first measuringtube, amounts to more than 0.03, especially more than 0.05 and/or lessthan 0.15. In supplementation to the sixth embodiment of the firstfurther development of the invention further development of theinvention additionally other, for example, plate-shaped, couplingelements of first type can be provided for forming inlet-sideoscillation nodes for vibrations of the measuring tubes in the measuringtransducer.

According to a seventh embodiment of the sixth embodiment of the firstfurther development of the invention further development of theinvention, it is additionally provided, that the first measuring tubeand the second measuring tube are parallel to one another at least overa region extending between the first coupling element of first type andthe second coupling element of first type, and that the third measuringtube and the fourth measuring tube are parallel to one another at leastover a region extending between the first coupling element of first typeand the second coupling element of first type.

In a second further development of the invention, the measuringtransducer additionally comprises a first coupling element of secondtype, for example, a plate shaped or rod shaped, first coupling elementof second type, which is affixed only to the first measuring tube and tothe third measuring tube and spaced both from the first coupling elementof first type as well as also from the second coupling element of firsttype for synchronizing vibrations, especially bending oscillations, ofthe first measuring tube and thereto equal frequency vibrations,especially bending oscillations, of the third measuring tube, as well asa second coupling element of second type, for example, a plate shaped orrod shaped, second coupling element of second type, which is affixedonly to the second measuring tube and to the fourth measuring tube andspaced both from the first coupling element of first type as well asalso from the second coupling element of first type, as well as alsofrom the first coupling element of second type, especially in such amanner, that the first and second coupling elements of second type areplaced in the measuring transducer lying opposite one another, forsynchronizing vibrations, especially bending oscillations, of the secondmeasuring tube and thereto equal frequency vibrations, especiallybending oscillations, of the fourth measuring tube. In supplementationthereof, the measuring transducer can further comprise a third couplingelement of second type, for example, a plate shaped or rod shaped, thirdcoupling element of second type, which is affixed only to the firstmeasuring tube and to the third measuring tube and spaced from the firstcoupling element of second type, for synchronizing vibrations,especially bending oscillations, of the first measuring tube and theretoequal frequency vibrations, especially bending oscillations, of thethird measuring tube, as well as a fourth coupling element of secondtype, for example, a plate shaped or rod shaped, fourth coupling elementof second type, which is affixed only to the second measuring tube andto the fourth measuring tube and spaced, in each case, from the secondand third coupling elements of second type, especially in such a manner,that the third and fourth coupling elements of second type are placedlying opposite one another in the measuring transducer, forsynchronizing vibrations, especially bending oscillations, of the secondmeasuring tube and thereto equal frequency vibrations, especiallybending oscillations, of the fourth measuring tube.

Moreover, the measuring transducer can comprise, additionally, a fifthcoupling element of second type, for example, a plate shaped or rodshaped, fifth coupling element of second type, which is affixed only tothe first measuring tube and to the third measuring tube and spaced fromthe first and third coupling elements of second type, for synchronizingvibrations, especially bending oscillations, of the first measuring tubeand thereto equal frequency vibrations, especially bending oscillations,of the third measuring tube, as well as a, for example, a plate shapedor rod shaped, sixth coupling element of second type, which is affixedonly to the second measuring tube and to the fourth measuring tube andspaced, in each case, from the second, fourth and fifth couplingelements of second type, especially in such a manner that the fifth andsixth coupling elements of second type are placed in the measuringtransducer lying opposite one another, for synchronizing vibrations,especially bending oscillations, of the second measuring tube andthereto equal frequency vibrations, especially bending oscillations, ofthe fourth measuring tube.

In a third further development of the invention, the measuringtransducer additionally comprises a sensor arrangement for producingoscillation measurement signals representing vibrations, especiallybending oscillations, of the measuring tubes, by reacting to vibrationsof the measuring tubes, especially bending oscillations excited by meansof the exciter mechanism. The sensor arrangement is, for example, anelectrodynamic sensor arrangement and/or is formed by means ofoscillation sensors constructed equally to one another.

In a first embodiment of the third further development of the invention,it is provided, that the sensor arrangement is formed by means of aninlet-side, first oscillation sensor, especially an electrodynamic,first oscillation sensor and/or a first oscillation sensordifferentially registering oscillations of the first measuring tuberelative to the second measuring tube, as well as by means of anoutlet-side, second oscillation sensor, especially an electrodynamic,second oscillation sensor and/or a second oscillation sensordifferentially registering oscillations of the first measuring tuberelative to the second measuring tube, especially in such a manner thata measuring length of the measuring transducer corresponding to a lengthof a section of a deflection curve of the first measuring tube extendingbetween the first oscillation sensor and the second oscillation sensoramounts to more than 500 mm, especially more than 600 mm and/or lessthan 1200 mm, and/or in such a manner that a caliber to measuring lengthratio of the measuring transducer, as defined by a ratio of a caliber ofthe first measuring tube to the measuring length of the measuringtransducer, amounts to more than 0.05, especially more than 0.09.Additionally, the first oscillation sensor can be formed by means of apermanent magnet held on the first measuring tube and a cylindrical coilpermeated by the magnetic field of the permanent magnet and held on thesecond measuring tube, and the second oscillation sensor by means of apermanent magnet held on the first measuring tube and a cylindrical coilpermeated by the magnetic field of the permanent magnet and held on thesecond measuring tube.

In a second embodiment of the third further development of theinvention, it is additionally provided, that the sensor arrangement isformed by means of an inlet-side, first oscillation sensor, especiallyan electrodynamic, first oscillation sensor and/or a first oscillationsensor differentially registering oscillations of the first measuringtube relative to the second measuring tube, by an outlet-side, secondoscillation sensor, especially an electrodynamic, second oscillationsensor and/or a second oscillation sensor differentially registeringoscillations of the first measuring tube relative to the secondmeasuring tube, by an inlet-side, third oscillation sensor, especiallyan electrodynamic, third oscillation sensor and/or a third oscillationsensor differentially registering oscillations of the third measuringtube relative to the fourth measuring tube, as well as by anoutlet-side, fourth oscillation sensor, especially an electrodynamic,fourth oscillation sensor and/or a fourth oscillation sensordifferentially registering oscillations of the third measuring tuberelative to the fourth measuring tube, especially in such a manner, thata measuring length of the measuring transducer corresponding to asection of a deflection curve of the first measuring tube extendingbetween the first oscillation sensor and the second oscillation sensoramounts to more than 500 mm, especially more than 600 mm and/or lessthan 1200 mm, and/or in such a manner that a caliber to measuring lengthratio of the measuring transducer, as defined by a ratio of a caliber ofthe first measuring tube to the measuring length of the measuringtransducer, amounts to more than 0.05, especially more than 0.09. Insuch case, in advantageous manner, the first and third oscillationsensors can be interconnected electrically in series in such a manner,that a combined oscillation measurement signal represents combinedinlet-side oscillations of the first and third measuring tubes relativeto the second and fourth measuring tube, and/or the second and fourthoscillation sensors can be interconnected electrically in series in sucha manner, that a combined oscillation measurement signal representscombined outlet-side oscillations of the first and third measuring tubesrelative to the second and fourth measuring tube. Alternatively or insupplementation, the first oscillation sensor can further be formed bymeans of a permanent magnet held on the first measuring tube and acylindrical coil permeated by the magnetic field of the permanent magnetand held on the second measuring tube, and the second oscillation sensorby means of a permanent magnet held on the first measuring tube and acylindrical coil permeated by the magnetic field of the permanent magnetand held on the second measuring tube, and/or the third oscillationsensor by means of a permanent magnet held on the third measuring tubeand a cylindrical coil permeated by the magnetic field of the permanentmagnet and held on the fourth measuring tube and the fourth oscillationsensor by means of a permanent magnet held on the third measuring tubeand a cylindrical coil permeated by the magnetic field of the permanentmagnet and held on the fourth measuring tube.

Moreover, the invention resides in an in-line measuring device formeasuring a density and/or a mass flow rate, especially also a totalmass flow totaled over a time interval, of a medium, especially of agas, a liquid, a powder or other flowable material flowing in apipeline, at least at times, especially with a mass flow rate of morethan 1000 t/h, which in-line measuring device, especially an in-linemeasuring device embodied as a compact device, comprises one of theaforementioned measuring transducers as well as a measuring deviceelectronics electrically coupled with the measuring transducer,especially also a measuring device electronics mechanically rigidlyconnected with the measuring transducer.

A basic idea of the invention is to use, instead of the tubearrangements with two measuring tubes, through which the medium flows inparallel, as usually used in the case of conventional measuringtransducers of large nominal diameter, tube arrangements with four bent,for example V-shaped or circular arc shaped, measuring tubes, throughwhich the medium flows in parallel, and so, on the one hand, to enablean optimal exploitation of the limited offering of space, while, on theother hand, being able to assure an acceptable pressure loss over abroad measuring range, especially also in the case of very high, massflow rates of far over 1000 t/h. Moreover, the effective flow crosssection of the tube arrangement resulting from the total cross sectionof the four measuring tubes can, in comparison to conventional measuringtransducers of equal nominal diameter and equal empty mass having onlytwo measuring tubes, be directly increased by more than 20%.

An advantage of the invention is additionally, among other things, that,through the application of curved measuring tubes, lasting mechanicalstresses, for example, as a result of thermally related expansion of themeasuring tubes or as a result of clamping forces introduced into themeasuring transducer because of the tube arrangement, are largelyprevented within the tube arrangement or at least kept very low and, asa result, the accuracy of measurement, as well as also the structuralintegrity of the measuring transducer, are safely obtained, even in thecase of extremely hot media, or in the case of temperature gradientsstrongly fluctuating within the tube arrangement as a function of time.Moreover, due to the symmetry characteristics of the tube arrangement,also those transverse forces caused by bending oscillations of curvedmeasuring tubes can largely be neutralized, which—as discussed, amongother things, in the initially mentioned EP-A 1 248 084 and U.S. Pat.No. 7,350,421—act essentially perpendicularly to the longitudinalsection planes of the measuring transducer, or its tube arrangement andcan be quite damaging for the accuracy of measurement of measuringtransducers of vibration-type.

A further advantage of the measuring transducer of the invention residesadditionally in the fact that predominantly established, structuraldesigns, such as regards materials used, joining technology,manufacturing steps, etc., can be applied, or must only be slightlymodified, whereby also manufacturing costs are, in total, quitecomparable to those of conventional measuring transducers. As a result,a further advantage of the invention is to be found in the fact that,thereby, not only an opportunity is created for implementingcomparatively compact measuring transducers of vibration-type also withlarge nominal diameters of over 150 mm, especially with a nominaldiameter of larger 250 mm, with manageable geometric dimensions andempty dimensions, but, additionally, also, this can be accomplished inan economically sensible manner.

The measuring transducer of the invention is, consequently, especiallysuitable for measuring flowable media guided in a pipeline having acaliber of larger 150 mm, especially of 300 mm or greater. Additionally,the measuring transducer is also suitable for measuring also mass flows,which are, at least at times, greater than 1000 t/h, especially, atleast at times, amounting to more than 1500 t/h, such as can occur e.g.in the case of applications for measuring petroleum, natural gas orother petrochemical materials.

The invention, as well as other advantageous embodiments thereof, willnow be explained in greater detail on the basis of examples ofembodiments presented in the figures of the drawing. Equal parts areprovided in the figures with equal reference characters; when requiredto avoid clutter or when it otherwise appears sensible, alreadymentioned reference characters are omitted in subsequent figures. Otheradvantageous embodiments or further developments, especially alsocombinations of first only individually explained aspects of theinvention, will become evident additionally from the figures of thedrawing, as well as also alone from the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In particular, the figures of the drawing show as follows:

FIGS. 1,2 an in-line measuring device serving, for example, as aCoriolis flow/density/viscosity measuring device, in perspective, alsopartially sectioned, side views;

FIGS. 3 a,b a projection of the in-line measuring device of FIG. 1 intwo different side views;

FIG. 4 a in perspective, side view, a measuring transducer ofvibration-type having a tube arrangement formed by means of four bentmeasuring tubes and installed in an in-line measuring device of FIG. 1;

FIG. 4 b the tube arrangement of FIG. 4 a in perspective, side view;

FIGS. 5 a,b a projection of the measuring transducer of FIG. 4 in twodifferent side views; and

FIGS. 6 a,b projections of a tube arrangement of the measuringtransducer of FIG. 4 in two different side views.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

While the invention is susceptible to various modifications andalternative forms, exemplary embodiments thereof have been shown by wayof example in the drawings and will herein be described in detail. Itshould be understood, however, that there is no intent to limit theinvention to the particular forms disclosed, but on the contrary, theintention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the invention as defined by theintended claims.

FIGS. 1, 2 show, schematically, an in-line measuring device 1,especially an in-line measuring device embodied as a Coriolis, massflow, and/or density, measuring device, which serves for registering amass flow m of a medium flowing in a pipeline (not shown) and forrepresenting such in a mass flow, measured value representing this massflow instantaneously. The medium can be practically any flowablematerial, for example, a powder, a liquid, a gas, a vapor, or the like.Alternatively or in supplementation, the in-line measuring device 1 can,in given cases, also be used for measuring a density ρ and/or aviscosity η of the medium. Especially, the in-line measuring device isprovided for measuring media, such as e.g. petroleum, natural gas orother petrochemical materials, which are flowing in a pipeline having acaliber greater than 250 mm, especially a caliber of 300 mm or more.Especially, the in-line measuring device is also provided for measuringflowing media of the aforementioned type, which are caused to flow witha mass flow rate of greater than 1000 t/h, especially greater than 1500t/h.

The in-line measuring device 1 comprises, for such purpose: A measuringtransducer 11 of vibration-type, through which the medium being measuredflows, during operation; as well as, electrically connected with themeasuring transducer 11, a measuring device electronics 12, which ishere not shown in detail, but, instead only schematically in the form ofa contained unit. In advantageous manner, the measuring deviceelectronics 12 is so designed that, during operation of the in-linemeasuring device 1, it can exchange measuring, and/or other operating,data with a measured value processing unit superordinated to it, forexample, a programmable logic controller (PLC), a personal computerand/or a work station, via a data transmission system, for example, ahardwired fieldbus system and/or wirelessly per radio. Furthermore, themeasuring device electronics 12 is so designed, that it can be fed by anexternal energy supply, for example, also via the aforementionedfieldbus system. For the case, in which the in-line measuring device 1is provided for coupling to a fieldbus, or other communication, system,the measuring device electronics 12, especially a programmable measuringdevice electronics, includes, additionally, a correspondingcommunication interface for data communication, e.g. for sending themeasured data to the already mentioned, programmable logic controller ora superordinated process control system.

FIGS. 4 a, 4 b, 5 a, 5 b, 6 a, 6 b show different representations of anexample of an embodiment for a measuring transducer 11 of vibration-typesuited for the in-line measuring device 1, especially one serving as aCoriolis, mass flow, density and/or viscosity, transducer, whichmeasuring transducer 11 is applied, during operation, in the course of apipeline (not shown), through which a medium to be measured, forexample, a powdered, liquid, gaseous or vaporous medium, is flowing. Themeasuring transducer 11 serves to produce, as already mentioned, in amedium flowing therethrough, such mechanical reaction forces, especiallyCoriolis forces dependent on mass flow, inertial forces dependent ondensity of the medium and/or frictional forces dependent on viscosity ofthe medium, which react measurably, especially registerably by sensor,on the measuring transducer. Derived from these reaction forcesdescribing the medium, by means of evaluating methods correspondinglyimplemented in the measuring device electronics in manner known to thoseskilled in the art, e.g. the mass flow, the density and/or the viscosityof the medium can be measured.

The measuring transducer 11 includes a transducer housing 7 ₁, which is,here, essentially tubular, and externally circularly cylindrical, andwhich serves, among other things, also as a support frame, in whichother components of the measuring transducer 11 serving for registeringthe at least one measured variable are accommodated to be protectedagainst external, environmental influences. In the example of anembodiment shown here, at least one middle segment of the transducerhousing 7 ₁ is formed by means of a straight, especially circularlycylindrical, tube, so that, for manufacture of the transducer housing,for example, also cost effective, welded or cast, standard tubes, forexample, of cast steel or forged steel, can be used.

An inlet-side, first housing end of the transducer housing 7 ₁ is formedby means of an inlet-side, first flow divider 20 ₁ and an outlet-side,second housing end of the transducer housing 7 ₁ is formed by means ofoutlet-side, second flow divider 20 ₂. Each of the two flow dividers 20₁, 20 ₂, which are, in this respect, formed as integral components ofthe housing, includes exactly four, for example, circularly cylindricalor tapered or conical, flow openings 20 _(1A), 20 _(1B), 20 _(1C), 20_(1D), or 20 _(2A), 20 _(2B), 20 _(2C), 20 _(2D), each spaced from oneanother and/or each embodied as an inner cone.

Moreover, each of the flow dividers 20 ₁, 20 ₂, for example,manufactured of steel, is provided with a flange 6 ₁, or 6 ₂, forexample, manufactured of steel, for connecting of the measuringtransducer 11 to a tubular segment of the pipeline serving for supplyingmedium to the measuring transducer, or to a tubular segment of suchpipeline serving for removing medium from the measuring transducer. Eachof the two flanges 6 ₁, 6 ₂ shows, according to an embodiment of theinvention, a mass of more than 50 kg, especially more than 60 kg and/orless than 100 kg. For leakage free, especially fluid tight, connectingof the measuring transducer with the, in each case, correspondingtubular segment of the pipeline, each of the flanges includesadditionally, in each case, a corresponding, as planar as possible,sealing surface 6 _(1A), or 6 _(2A). A distance between the two sealingsurfaces 6 _(1A), 6 _(2A) of both flanges defines, thus, for practicalpurposes, an installed length, L₁₁, of the measuring transducer 11. Theflanges are dimensioned, especially as regards their inner diameter,their respective sealing surface as well as the flange bores serving foraccommodating corresponding connection bolts, according to the nominaldiameter D₁₁ provided for the measuring transducer 11 as well as thetherefor, in given cases, relevant industrial standards, correspondingto a caliber of the pipeline, in whose course the measuring transduceris to be used.

As a result of the large nominal diameter lastly desired for themeasuring transducer, its installed length L₁₁ amounts, according to anembodiment of the invention, to more than 1200 mm. Additionally, it is,however, provided that the installed length of the measuring transducer11 is kept as small as possible, especially smaller than 3000 mm. Theflanges 6 ₁, 6 ₂ can, as well as also directly evident from FIG. 4 a andsuch as quite usual in the case of such measuring transducers, bearranged, for this purpose, as near as possible to the flow openings ofthe flow dividers 20 ₁, 20 ₂, in order so to provide an as short aspossible inlet, or outlet, as the case may be, region in the flowdividers and, thus, in total, to provide an as short as possibleinstalled length L₁₁ of the measuring transducer, especially aninstalled length L₁₁ of less than 3000 mm. For an as compact as possiblemeasuring transducer and especially also in the case of desired highmass flow rates of over 1000 t/h, according to another embodiment of theinvention, the installed length and the nominal diameter of themeasuring transducer are so dimensioned and matched to one another, thata nominal diameter to installed length ratio D₁₁/L₁₁ of the measuringtransducer, as defined by a ratio of the nominal diameter D₁₁ of themeasuring transducer to the installed length L₁₁ of the measuringtransducer is smaller than 0.3, especially smaller than 0.2 and/orgreater than 0.1.

In an additional embodiment of the measuring transducer, the transducerhousing comprises an essentially tubular, middle segment. Additionally,it is provided that the transducer housing is so dimensioned, that ahousing inner diameter to nominal diameter ratio of the measuringtransducer defined by a ratio of the largest housing inner diameter tothe nominal diameter of the measuring transducer is, indeed, greaterthan 0.9, however, smaller than 1.5, as much as possible, however,smaller than 1.2.

In the case of the here illustrated example of an embodiment, thereadjoin on the inlet and outlet sides of the middle segment,additionally, likewise tubular end segments of the transducer housing.For the case illustrated in the example of an embodiment, in which themiddle segment and the two end segments, as well as also the flowdividers connected with the respective flanges in the inlet and outletregions all have the same inner diameter, the transducer housing can inadvantageous manner also be formed by means of a one piece, for example,cast or forged, tube, on whose ends the flanges are formed or welded,and in the case of which the flow dividers are formed by means of plateshaving the flow openings, especially plates somewhat spaced from theflanges and welded to the inner wall orbitally and/or by means of laser.Especially for the case, in which the mentioned housing inner diameterto nominal diameter ratio of the measuring transducer is selected equalto one, for manufacture of the transducer housing, for example, a tubematched to the pipeline to be connected to as regards caliber, wallthickness and material and, in that respect, also as regards the allowedoperating pressure and with correspondingly suitable length can be used.For simplifying the transport of the measuring transducer, or thetotally therewith formed, in-line measuring device, additionally, suchas, for example, also provided in the initially mentioned U.S. Pat. No.7,350,421, transport eyes can be provided affixed on the inlet side andon the outlet side externally on the transducer housing.

For conveying the medium flowing, at least at times, through pipelineand measuring transducer, the measuring transducer of the inventioncomprises, additionally, a tube arrangement having exactly four curved,or bent, for example at least sectionally V-shaped, or, as shown hereschematically, at least sectionally circular arc shaped, measuring tubes18 ₁, 18 ₂, 18 ₃, 18 ₄ held oscillatably in the transducer housing 10.The four measuring tubes, in this case, measuring tubes of equal lengthand pairwise parallel, communicate, in each case, with the pipelineconnected to the measuring transducer and are, at least at times, causedduring operation to vibrate in at least one oscillatory mode, theso-called wanted mode, suited for ascertaining the physical, measuredvariable. Especially suited as wanted mode and naturally inherent toeach of the measuring tubes 18 ₁, 18 ₂, 18 ₃, and 18 ₄ is e.g. a bendingoscillation, fundamental mode, which at a minimum bending oscillation,resonance frequency, f₁₈₁, f₁₈₂, f₁₈₃, or f₁₈₄, shows exactly oneoscillatory antinode.

Of the four measuring tubes, a first measuring tube 18 ₁ opens with aninlet-side, first measuring tube end into a first flow opening 20 _(1A)of the first flow divider 20 ₁ and with an outlet-side, second measuringtube end into a first flow opening 20 _(2A) of the second flow divider20 ₂, a second measuring tube 18 ₂ opens with an inlet-side, firstmeasuring tube end into a second flow opening 20 _(1B) of the first flowdivider 20 ₁ and with an outlet-side, second measuring tube end into asecond flow opening 20 _(2B) of the second flow divider 20 ₂, a thirdmeasuring tube 18 ₃ opens with an inlet-side, first measuring tube endinto a third flow opening 20 _(1C) of the first flow divider 20 ₁ andwith an outlet-side, second measuring tube end into a third flow opening20 _(2C) of the second flow divider 20 ₂ and a fourth measuring tube 18₄ opens with an inlet-side, first measuring tube end into a fourth flowopening 20 _(1C) of the first flow divider 20 ₁ and with an outlet-side,second measuring tube end into a fourth flow opening 20 _(2C) of thesecond flow divider 20 ₂. The four measuring tubes 18 ₁, 18 ₂, 18 ₃, 18₄ are, thus, connected to the flow dividers 20 ₁, 20 ₂, especiallyequally constructed flow dividers 20 ₁, 20 ₂, to form flow pathsconnected in parallel, and, indeed, in a manner enabling vibrations,especially bending oscillations, of the measuring tubes relative to oneanother, as well as also relative to the transducer housing.Additionally, it is provided, that the four measuring tubes 18 ₁, 18 ₂,18 ₃, 18 ₄ are held oscillatably in the transducer housing 7 ₁ only bymeans of said flow dividers 20 ₁, 20 ₂.

In the case of the measuring transducer of the invention, the measuringtubes are, as directly evident also from the combination of FIGS. 2, 4 aand 4 b, so embodied and arranged in the measuring transducer, that thetube arrangement shows, lying both between the first measuring tube 18 ₁and the third measuring tube 18 ₃ as well as also between the secondmeasuring tube 18 ₂ and the fourth measuring tube 18 ₄, a firstimaginary longitudinal-section plane XZ, with respect to which the tubearrangement is mirror symmetric, and that the tube arrangement showsfurther, perpendicular to its imaginary first longitudinal-section planeXZ, and extending both between the first measuring tube 18 ₁ and secondmeasuring tube 18 ₂ as well as also between the third measuring tube 18₃ and fourth measuring tube 18 ₄, a second imaginarylongitudinal-section plane YZ, with respect to which the tubearrangement likewise is mirror symmetric. As a result of this, not onlyare stresses generated by possible thermally related expansion of themeasuring tubes within the tube arrangement minimized, but alsotransverse forces possibly induced by the bending oscillations of thebent measuring tubes within the tube arrangement and acting essentiallyperpendicularly to the line of intersection of the two aforementioned,imaginary, longitudinal-section planes can be largely neutralized, notlastly also those transverse forces mentioned, among other things, alsoin the initially mentioned EP-A 1 248 084 and U.S. Pat. No. 7,350,421,directed essentially perpendicularly to the first imaginarylongitudinal-section plane XZ.

For additional symmetrization of the measuring transducer and, thus,also for the additional simplifying of its construction, the two flowdividers 20 ₁, 20 ₂ are, according to an additional embodiment of theinvention, additionally so embodied and so arranged in the measuringtransducer, that, as also schematically presented in FIGS. 4 a and 4 b,an imaginary first connecting axis Z₁ of the measuring transducerimaginarily connecting the first flow opening 20 _(1A) of the first flowdivider 20 ₁ with the first flow opening 20 _(2A) of the second flowdivider 20 ₂ extends parallel to an imaginary second connecting axis Z₂of the measuring transducer imaginarily connecting the second flowopening 20 _(1B) of the first flow divider 20 ₁ with the second flowopening 20 _(2B) of the second flow divider 20 ₂, and that an imaginarythird connecting axis Z₃ of the measuring transducer imaginarilyconnecting the third flow opening 20 _(1C) of the first flow divider 20₁ with the third flow opening 20 _(2D) of the second flow divider 20 ₂extends parallel to an imaginary fourth connecting axis Z₄ of themeasuring transducer imaginarily connecting the fourth flow opening 20_(1D) the first flow divider 20 ₁ with the fourth flow opening 20 _(2B)the second flow divider 20 ₂. As shown in FIGS. 4 a and 4 b, the flowdividers are additionally so embodied and so arranged in the measuringtransducer, that the connecting axes Z₁, Z₂, Z₃, Z₄ also are parallel toa principal flow axis L of the measuring transducer essentially aligningwith the pipeline and/or coincident with the aforementioned line ofintersection of the two imaginary longitudinal-section planes XZ, YZ ofthe tube arrangement. Furthermore, the two flow dividers 20 ₁, 20 ₂ canadditionally also be so embodied and so arranged in the measuringtransducer, that a first imaginary longitudinal-section plane XZ₁ of themeasuring transducer, within which the first imaginary connecting axisZ₁ and the second imaginary connecting axis Z₂ extend, is parallel to asecond imaginary longitudinal-section plane XZ₂ of the measuringtransducer, within which the imaginary third connecting axis Z₃ and theimaginary fourth connecting axis Z₄ extend.

Moreover, the measuring tubes are, according to an additional embodimentof the invention, additionally so embodied and so arranged in themeasuring transducer, that the imaginary first longitudinal-sectionplane XZ of the tube arrangement, as, among other things, also evidentfrom the combination of FIGS. 3 a and 4 a, lies between theaforementioned first imaginary longitudinal-section plane XZ₁ of themeasuring transducer and the aforementioned second imaginarylongitudinal-section plane XZ₂ of the measuring transducer, for example,also such that the first longitudinal-section plane XZ of the tubearrangement is parallel to the first and second longitudinal-sectionplanes XZ₁,XZ₂ of the measuring transducer. Additionally, the measuringtubes are so embodied and arranged in the measuring transducer, thatequally also the second imaginary longitudinal-section plane YZ of thetube arrangement extends between the third imaginarylongitudinal-section plane YZ₁ of the measuring transducer and thefourth imaginary longitudinal-section plane YZ₂ of the measuringtransducer, for instance, in such a manner, that the second imaginarylongitudinal-section plane YZ of the tube arrangement is parallel to thethird imaginary longitudinal-section plane YZ₁ of the measuringtransducer and parallel to the fourth imaginary longitudinal-sectionplane YZ₂ of the measuring transducer.

The measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄, or the therewith formed,tube arrangement of the measuring transducer 11, are, such as directlyevident from the combination of FIGS. 1, 2 and 4 a, encased by thetransducer housing 7 ₁, in the illustrated case practically completely.Transducer housing 7 ₁ serves, in this regard, thus not only as supportframe or holder of the measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄, but alsofor protecting them, as well as also other components of the measuringtransducer placed within the transducer housing 7 ₁, from externalenvironmental influences, such as e.g. dust or water spray. Moreover,the transducer housing 7 ₁ can additionally also be so embodied and sodimensioned, that it can, in the case of possible damage to one or aplurality of the measuring tubes, e.g. through crack formation orbursting, completely retain outflowing medium up to a required maximumpositive pressure in the interior of the transducer housing 7 ₁ as longas possible, wherein such critical state can, such as, for example, alsoindicated in the initially mentioned U.S. Pat. No. 7,392,709, beregistered and signaled by means of corresponding pressure sensorsand/or on the basis of operating parameters produced internally, duringoperation, by the mentioned measuring device electronics 12. Used asmaterial for the transducer housing 7 ₁ can be, accordingly, especially,steels, such as, for instance, structural steel, or stainless steel, oralso other suitable, or usually suitable for this application, highstrength materials.

According to an embodiment of the invention, the four measuring tubes 18₁, 18 ₂, 18 ₃, 18 ₄ are additionally so embodied and so installed in themeasuring transducer 11, that at least the minimum bending oscillation,resonance frequencies f₁₈₁, f₁₈₂ of the first and second measuring tubes18 ₁, 18 ₂ are essentially equal and at least the minimum bendingoscillation, resonance frequencies f₁₈₃, f₁₈₄ of the third and fourthmeasuring tubes 18 ₃, 18 ₄ are essentially equal.

According to an additional embodiment of the invention, at least thefirst and second measuring tubes 18 ₁, 18 ₂ are of equal construction asregards a material, of which their tube walls are composed, and/or asregards their geometric tube dimensions, especially a measuring tubelength, a tube wall thickness, a tube outer diameter and/or a caliber.Additionally, also at least the third and fourth measuring tubes 18 ₃,18 ₄ are of equal construction as regards a material, of which theirtube walls are composed, and/or as regards their geometric tubedimensions, especially a measuring tube length, a tube wall thickness, atube outer diameter and/or a caliber, so that, as a result, the fourmeasuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ are, at least pairwise,essentially of equal construction. According to an additional embodimentof the invention, it is, in such case, additionally provided, toconstruct both the third measuring tube as well as also the fourthmeasuring tube, such that the two measuring tubes are different from thefirst measuring tube and from the second measuring tube, as regardstheir respective geometric tube dimensions, especially a measuring tubelength, a tube wall thickness, a tube outer diameter and/or a caliber,especially in such a manner, that the minimum bending oscillation,resonance frequencies of the four measuring tubes are only pairwiseequal. Through the, thus, created symmetry breaking in the case of thefour measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄, among other things, thesensitivity, the oscillatory behavior, especially the mechanicaleigenfrequencies, and/or the cross sensitivity to the primary, measuringinfluencing, disturbance variables, such as, for instance, atemperature, or pressure, distribution, the loading of the medium withimpurities, etc., of the two, in this respect, mutually different,measuring tube pairs 18 ₁, 18 ₂, or 18 ₃, 18 ₄, can be matched, withtargeting, to one another and, thus, an improved diagnosis of themeasuring transducer, during operation, can be enabled. Of course, thefour measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ can, in case required,however, also be of equal construction as regards a material, of whichtheir tube walls are composed, and/or as regards their geometric tubedimensions, especially a measuring tube length, a tube wall thickness, atube outer diameter, a shape of the associated deflection curve and/or acaliber, especially in such a manner, that, as a result, the minimumbending oscillation, resonance frequencies of all four empty measuringtubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ or all four measuring tubes 18 ₁, 18 ₂, 18₃, 18 ₄, through which a homogeneous medium is uniformly flowing, areessentially equal.

Suited as material for the tube walls of the measuring tubes is, again,especially, titanium, zirconium or tantalum. However, serving asmaterial for the four measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ can be alsopractically any other therefor usually applied, or at least suitable,material, especially such with a thermal expansion coefficient as smallas possible and a yield point as high as possible. For most applicationsof industrial measurements technology, especially also in thepetrochemical industry, consequently, also measuring tubes of stainlesssteel, for example, also duplex steel or super duplex steel, wouldsatisfy the requirements as regards mechanical strength, chemicalresistance as well as thermal requirements, so that in numerous cases ofapplication of the transducer housing 7 ₁, the flow dividers 20 ₁, 20 ₂,as well as also the tube walls of the measuring tubes 18 ₁, 18 ₂, 18 ₃,18 ₄ can, in each case, be made of steel of, in each case, sufficientlyhigh quality, this being of advantage, especially as regards material,and manufacturing, costs, as well as also as regards the thermallyrelated dilation behavior of the measuring transducer 11, duringoperation.

In an additional advantageous embodiment of the invention, the flowopenings of the first flow divider 20 ₁ are additionally so arranged,that those imaginary areal center of gravity, which belong to the—herecircularly shaped—cross sectional areas of the flow openings of thefirst flow divider form the vertices of an imaginary rectangle or of animaginary square, wherein said cross sectional areas lie, again, in ashared imaginary, cross sectional plane of the first flow dividerextending perpendicular to a longitudinal axis L of the measuringtransducer—, for example, a longitudinal axis extending within the firstlongitudinal-section plane XZ of the tube arrangement, or parallel to oreven coincident with the mentioned principal flow axis of the measuringtransducer—, or perpendicular to the longitudinal-section planes of themeasuring transducer. Additionally, also the flow openings of the secondflow divider 20 ₂ are so arranged, that imaginary areal centers ofgravity associated with—here likewise circularly shaped—cross sectionalareas of the flow openings of the second flow divider 20 ₂ form thevertices of an imaginary rectangle, or square, wherein said crosssectional areas lie, again, in a shared imaginary, cross sectional planeof the second flow divider extending perpendicular to the mentioned mainflow, or also longitudinal, axis, L of the measuring transducer, orperpendicular to the longitudinal-section planes of the measuringtransducer. As a result of this, an envelope of the four measuring tubes18 ₁, 18 ₂, 18 ₃, 18 ₄ forms practically a straight, for example, aroundthe mentioned principal flow axis, or longitudinal axis L of themeasuring transducer, rotationally symmetric body having arectangular—or also square-like base having an at least two-foldsymmetry, whereby the space requirement of the tube arrangement formedby means of the four measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ can beminimized in a manner supporting the compactness of the measuringtransducer 11 as a whole.

According to an additional embodiment of the invention, each of themeasuring tubes is additionally so arranged in the measuring transducer,that a smallest lateral separation of each of the four measuring tubes(here, of equal length) from a housing side wall of the transducerhousing is, in each case, greater than zero, especially, however,greater than 3 mm and/or greater than twice a respective tube wallthickness, or that a smallest lateral separation between two neighboringmeasuring tubes is, in each case, greater than 3 mm and/or greater thanthe sum of their respective tube wall thicknesses. Accordingly,additionally, each of the flow openings is so arranged, that a smallestlateral separation of each of the flow openings from a housing side wallof the transducer housing 7 ₁ is, in each case, greater than zero,especially greater than 3 mm and/or greater than twice a smallest tubewall thickness of the measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄, or that asmallest lateral separation between the flow openings is greater than 3mm and/or greater than twice a smallest tube wall thickness of themeasuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄. For such purpose, according toan additional embodiment of the invention, the four measuring tubes 18₁, 18 ₂, 18 ₃, 18 ₄ and the transducer housing 7 ₁ are so dimensionedand matched to one another, that a housing to measuring tube, innerdiameter ratio of the measuring transducer, as defined by a ratio of thelargest housing inner diameter to a caliber at least of the firstmeasuring tube is greater than 3, especially greater than 4 and/orsmaller than 10. Alternatively, or in supplementation, the measuringtubes according to an additional embodiment of the invention are sobent, or curved, and so arranged, that a caliber to height ratio of thetube arrangement, defined by a ratio of the caliber, D₁₈, at least ofthe first measuring tube to a maximal lateral expanse of the tubearrangement, measured from a peak of the first measuring tube to a peakof the third measuring tube, amounts to more than 0.1, especially morethan 0.2 and/or less than 0.35.

As already initially mentioned, in the case of the measuring transducer11, the reaction forces required for the measuring are effected in themedium being measured by causing the measuring tubes 18 ₁, 18 ₂, 18 ₃,18 ₄ to oscillate in the so-called wanted mode. For such purpose, themeasuring transducer comprises additionally an exciter mechanism 5formed by means of at least one electromechanical, for example,electrodynamic, oscillation exciter acting on the measuring tubes 18 ₁,18 ₂, 18 ₃, 18 ₄, and serving for causing each of the measuring tubes,operationally, at least at times, to execute, and to maintain,oscillations suitable, in each case, for the particular measuring,especially bending oscillations, in the so-called wanted mode, with, ineach case, sufficiently large oscillation amplitude for producing andregistering the above named reaction forces in the medium. The at leastone oscillation exciter serves, in such case, especially for convertingan electrical excitation power P_(exc) fed from a correspondingmeasuring, and operating, circuit e.g. of the above named Coriolis, massflow meter into such, e.g. pulsating or harmonic, exciter forces Fexc,which act, as simultaneously as possible, uniformly, however, withopposite sense, on the measuring tubes. The exciter forces F_(exc) canbe tuned, in manner known, per se, to those skilled in the art, by meansprovided in the already mentioned measuring, and operating, electronics,e.g. by means of an electrical current, and/or voltage, control circuit,as regards their amplitude, and e.g. by means of phase control loop(PLL), as regards their frequency; compare, for this, for example, alsoU.S. Pat. No. 4,801,897 or U.S. Pat. No. 6,311,136.

As a result of medium flowing through the measuring tubes excited tooscillations in the wanted mode, there are induced in the mediumCoriolis forces, which, in turn, effect deformations of the measuringtubes corresponding to an additional, higher oscillation mode of themeasuring tubes, the so-called Coriolis mode. For example, the measuringtubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ can, during operation, be excited, by theelectromechanical exciter mechanism acting thereon, to bendingoscillations, especially to an instantaneous mechanical eigenfrequencyof the tube arrangement formed by means of the four measuring tubes 18₁, 18 ₂, 18 ₃, 18 ₄, in the case of which they are—at leastpredominantly—laterally deflected and, such as directly evident from thecombination of FIG. 3 a, 3 b, or 6 a, 6 b, are caused to oscillatepairwise relative to one another with essentially opposite phase. Thisoccurs, especially, in such a manner, that vibrations executed by eachof the measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ during operation at thesame time, at least at times and/or at least partially, in each case,are developed as bending oscillations about an imaginary oscillatoryaxis connecting the first and the, in each case, associated secondmeasuring tube end of the respective measuring tube, and, in each case,parallel to the mentioned connecting axes Z₁, Z₂, Z₃, Z₄, wherein thefour oscillatory axes in the here illustrated example of an embodimentare equally parallel to one another, as well as also to the imaginarylongitudinal axis L of the total measuring transducer imaginarilyconnecting the two flow dividers through a center of mass of themeasuring transducer. In other words, the measuring tubes can, as quiteusual in the case of measuring transducers of vibration-type, in eachcase, be caused to oscillate at least sectionally in a bendingoscillation mode in the manner of a string held at both ends, or in themanner of a terminally clamped cantilever.

In an additional embodiment of the invention, the measuring tubes 18 ₁,18 ₂, 18 ₃, 18 ₄ are excited by means of the exciter mechanism 5, duringoperation, at least partially, especially predominantly, to bendingoscillations, which have a bending oscillation frequency, which is aboutequal to an instantaneous mechanical resonance frequency of the tubearrangement comprising the four measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄or which at least lies in the vicinity of such an eigen—, or resonance,frequency. The instantaneous mechanical bending oscillation resonancefrequencies are, in such case, as is known, dependent in special measureon size, shape and material of the measuring tubes 18 ₁, 18 ₂, 18 ₃, 18₄, as well as also on an instantaneous density of the medium flowingthrough the measuring tubes, and can, thus, during operation of themeasuring transducer, be variable within a wanted frequency band havingan expanse of several kilohertz. In the exciting of the measuring tubesto a bending oscillation resonance frequency, on the one hand, anaverage density of the medium instantaneously flowing through the fourmeasuring tubes can be easily ascertained on the basis of theinstantaneously excited oscillation frequency. On the other hand, also,in such manner, the electrical power instantaneously required formaintaining the oscillations excited in the wanted mode can beminimized. Especially, the four measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄,driven by the exciter mechanism, additionally, are, at least at times,caused to oscillate with essentially equal oscillation frequency,especially at a shared natural mechanical eigenfrequency. Moreover, itis provided that the measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄, caused tooscillate at essentially equal frequency, are so excited, that, at leastin the case of no flowing medium, the first and third measuring tubes 18₁, 18 ₃ oscillate essentially synchronously relative to one another,i.e. with essentially equal oscillation form, essentially equal phaseposition and about equal oscillation amplitude. In manner analogousthereto, in the case of this embodiment of the invention, also thesecond and fourth measuring tubes 18 ₂, 18 ₄ are caused to oscillateessentially synchronously relative to one another.

The exciter mechanism according to an embodiment of the invention, isembodied in such a manner that, therewith, the first measuring tube 18 ₁and the second measuring tube 18 ₂ are excitable, during operation, toopposite phase, bending oscillations and the third measuring tube 18 ₃and the fourth measuring tube 18 ₄, during operation, to opposite phasebending oscillations. In an additional embodiment of the invention, theexciter mechanism 5 is formed therefor by means of a first oscillationexciter 5 ₁, especially an electrodynamic, first oscillation exciter 5 ₁and/or a first oscillation exciter 5 ₁ differentially excitingoscillations of the first measuring tube 18 ₁ relative to the secondmeasuring tube 18 ₂.

Additionally, it is provided, that the first oscillation exciter 5 ₁ isan oscillation exciter of electrodynamic type acting simultaneously,especially differentially, on at least two of the measuring tubes 18 ₁,18 ₂, 18 ₃, 18 ₄. Accordingly, the first oscillation exciter 5 ₁ isformed additionally by means of a permanent magnet held on the firstmeasuring tube and a cylindrical coil permeated by the magnetic field ofthe permanent magnet and held on the second measuring tube, especiallyin such a manner of a coil, plunging arrangement, in the case of whichthe cylindrical coil is arranged coaxially to the permanent magnet andthe permanent magnet is embodied in the form of an armature movedplungingly within the coil. In a further development of the invention,the exciter mechanism comprises additionally a second oscillationexciter 5 ₂, especially an electrodynamic, second oscillation exciter 5₂ and/or a second oscillation exciter 5 ₂ constructed equally to thefirst oscillation exciter 5 ₁ and/or differentially excitingoscillations of the third measuring tube 18 ₃ relative to the fourthmeasuring tube 18 ₄. The two oscillation exciters can, in advantageousmanner, be interconnected electrically in series, especially in such amanner, that a combined driver signal excites oscillations of the firstand third measuring tubes 18 ₁, 18 ₃ together relative to the second andfourth measuring tubes 18 ₂, 18 ₄. In an additional embodiment, thesecond oscillation exciter 5 ₂ is formed by means of a permanent magnetheld on the third measuring tube and a cylindrical coil permeated by themagnetic field of the permanent magnet and held on the fourth measuringtube.

As, amongst others, also presented in FIG. 4 a, 4 b, or 6 b, the firstoscillation exciter 5 ₁ can be arranged above the first and secondmeasuring tubes 18 ₁, 18 ₂ and, thus, also above a center of gravity ofthe tube arrangement lying in an imaginary cross sectional plane XY ofthe tube arrangement passing through the installed position of saidoscillation exciter and, here, in each case, perpendicular to the firstimaginary longitudinal-section plane XZ and to the second imaginarylongitudinal-section plane YZ of the tube arrangement. In the example ofan embodiment shown here, the tube arrangement is additionally alsomirror symmetric with respect to the aforementioned imaginary crosssectional plane XY. In the example of an embodiment shown here, the tubearrangement is, as directly evident from the combination of FIGS. 4 a, 4b, 5 a, 5 b and 6 a, additionally so embodied and so placed in themeasuring transducer housing, that, as a result, not only the sharedline of intersection of the first and second imaginarylongitudinal-section planes XZ, YZ of the tube arrangement is parallelto, or coincident with, the longitudinal axis L, but, also, a sharedline of intersection of the first longitudinal-section plane XZ and thecross sectional plane XY is parallel to an imaginary transverse axis Qof the measuring transducer perpendicular to the longitudinal axis L anda shared line of intersection of the second longitudinal-section planeYZ and the cross sectional plane XY is parallel to an imaginary verticalaxis H of the measuring transducer perpendicular to the longitudinalaxis L.

It is noted here, additionally, that, although the oscillation exciterof the exciter mechanism illustrated in the example of an embodimentacts, in each case, about centrally on the measuring tubes,alternatively or in supplementation also oscillation exciters acting onthe inlet and on the outlet sides on the respective measuring tubes canbe used, for instance in the manner of the exciter mechanisms proposedin U.S. Pat. No. 4,823,614, U.S. Pat. No. 4,831,885, or US-A2003/0070495.

As evident from FIGS. 2, 4 a, 4 b, 5 a and 5 b and usual in the case ofmeasuring transducers of the type being discussed, additionally providedin the measuring transducer 11 is a sensor arrangement 19, for example,an electrodynamic sensor arrangement, reacting to vibrations of themeasuring tubes 18 ₁, 18 ₂, 18 ₃, or 18 ₄, especially inlet, andoutlet-side vibrations, especially bending oscillations excited by meansof the exciter mechanism 5, for producing oscillation measurementsignals representing vibrations, especially bending oscillations, of themeasuring tubes and influenced, for example, as regards a frequency, asignal amplitude and/or a phase position—relative to one another and/orrelative to the driver signal—by the measured variable to be registered,such as, for instance, the mass flow rate and/or the density and aviscosity of the medium, respectively.

In an additional embodiment of the invention, the sensor arrangement isformed by means of an inlet-side, first oscillation sensor 19 ₁,especially an electrodynamic, first oscillation sensor and/or a firstoscillation sensor differentially registering at least oscillations ofthe first measuring tube 18 ₁ relative to the second measuring tube 18₂, as well as an outlet-side, second oscillation sensor 19 ₂, especiallyan electrodynamic, second oscillation sensor and/or a second oscillationsensor differentially registering at least oscillations of the firstmeasuring tube 18 ₁ relative to the second measuring tube 18 ₂, whichtwo oscillation sensors deliver, respectively, a first, and a second,oscillation measurement signal reacting to movements of the measuringtubes 18 ₁, 18 ₂, 18 ₃, 18 ₄, especially their lateral deflectionsand/or deformations. This, especially, in such a manner, that at leasttwo of the oscillation measurement signals delivered by the sensorarrangement 19 have a phase shift relative to one another, whichcorresponds to, or depends on, the instantaneous mass flow rate of themedium flowing through the measuring tubes, as well as, in each case, asignal frequency, which depends on an instantaneous density of themedium flowing in the measuring tubes. The two oscillation sensors 19 ₁,19 ₂, for example, oscillation sensors constructed equally to oneanother, can, for such purpose—such as quite usual in the case ofmeasuring transducers of the type being discussed—be placed essentiallyequidistantly from the first oscillation exciter 5 ₁ in the measuringtransducer 11. Moreover, the oscillation sensors of the sensorarrangement 19 can, at least, insofar as they are of equal constructionto that of the at least one oscillation exciter of the exciter mechanism5, work analogously to its principle of action, for example, thus belikewise of electrodynamic type. In a further development of theinvention, the sensor arrangement 19 is additionally formed also bymeans of an inlet-side, third oscillation sensor 19 ₃, especially anelectrodynamic, oscillation sensor and/or an oscillation sensordifferentially registering oscillations of the third measuring tube 18 ₃relative to the fourth measuring tube 18 ₄, as well as an outlet-side,fourth oscillation sensor 19 ₄, especially an electrodynamic, fourthoscillation sensor 19 ₄ and/or an electrodynamic oscillation sensordifferentially registering oscillations of the third measuring tube 18 ₃relative to the fourth measuring tube 18 ₄. For additional improving ofthe signal quality, as well as also for simplifying the measuring deviceelectronics 12 receiving the measurement signals, furthermore, the firstand third oscillation sensors 19 ₁, 19 ₃ can be electrically in seriesinterconnected, for example, in such a manner, that a combinedoscillation measurement signal represents combined inlet-sideoscillations of the first and third measuring tubes 18 ₁, 18 ₃ relativeto the second and fourth measuring tubes 18 ₂, 18 ₄. Alternatively or insupplementation, also the second and fourth oscillation sensors 19 ₂, 19₄ can be electrically in series interconnected in such a manner, that acombined oscillation measurement signal of both oscillation sensors 19₂, 19 ₄ represents combined outlet-side oscillations of the first andthird measuring tubes 18 ₁, 18 ₃ relative to the second and fourthmeasuring tubes 18 ₂, 18 ₄.

For the aforementioned case, that the oscillation sensors of the sensorarrangement 19, especially oscillation sensors constructed equally toone another, should register oscillations of the measuring tubesdifferentially and electrodynamically, the first oscillation sensor 19 ₁is formed by means of a permanent magnet held to the first measuringtube—here in the region of oscillations to be registered on the inletside—and a cylindrical coil permeated by the magnetic field of thepermanent magnet and held to the second measuring tube—herecorrespondingly likewise in the region of oscillations to be registeredon the inlet side—, and the second oscillation sensor 19 ₂ is formed bymeans of a permanent magnet held—in the region of oscillations to beregistered on the outlet side—to the first measuring tube and acylindrical coil permeated by the magnetic field of the permanent magnetand held to the second measuring tube—here correspondingly likewise inthe region of oscillations to be registered on the outlet side. Equally,additionally also the, in given cases, provided, third oscillationsensor 19 ₃ can correspondingly be formed by means of a permanent magnetheld to the third measuring tube and a cylindrical coil permeated by themagnetic field of the permanent magnet and held to the fourth measuringtube, and the, in given cases, provided, fourth oscillation sensor 19 ₄by means of a permanent magnet held to the third measuring tube and acylindrical coil permeated by the magnetic field of the permanent magnetand held to the fourth measuring tube.

It is to be noted here additionally that, although, in the case of theoscillation sensors of the sensor arrangement 19 illustrated in theexample of an embodiment, the oscillation sensor is, in each case, ofelectrodynamic type, thus, in each case, formed by means of acylindrical magnet coil affixed to one of the measuring tubes and atherein plunging permanent magnet correspondingly affixed to anoppositely lying measuring tube, additionally also other oscillationsensors known to those skilled in the art, such as e.g. optoelectronicsensors, can be used for forming the sensor arrangement. Furthermore,such as quite usual in the case of measuring transducers of the typebeing discussed, supplementally to the oscillation sensors, other,especially auxiliary sensors, or sensors registering disturbancevariables, can be provided in the measuring transducer, such as e.g.acceleration sensors, pressure sensors and/or temperature sensors, bymeans of which, for example, the ability of the measuring transducer tofunction and/or changes of the sensitivity of the measuring transducerto the measured variables primarily to be registered, especially themass flow rate and/or the density, as a result of cross sensitivities,or external disturbances, can be monitored and, in given cases,correspondingly compensated.

For assuring an as high as possible sensitivity of the measuringtransducer to the mass flow, according to an additional embodiment ofthe invention, the measuring tubes and the oscillation sensors are soarranged in the measuring transducer, that a measuring length, L₁₉, ofthe measuring transducer corresponding to a separation between the firstoscillation sensor 19 ₁ and the second oscillation sensor 19 ₂ measuredalong a deflection curve of the first measuring tube amounts to morethan 500 mm, especially more than 600 mm.

The exciter mechanism 5 and the sensor arrangement 19 are additionally,such as usual in the case of such measuring transducers, coupled insuitable manner (for example, hardwired by means of corresponding cableconnections) with a measuring, and operating, circuit correspondinglyprovided in the measuring device electronics. The measuring, andoperating, circuit, in turn, produces, on the one hand, an excitersignal correspondingly driving the exciter mechanism 5, for example, anexciter signal controlled as regards an exciter current and/or anexciter voltage. On the other hand, the measuring, and operating,circuit receives the oscillation measurement signals of the sensorarrangement 19 and generates, therefrom, sought measured values, which,for example, can represent a mass flow rate, a totaled mass flow, adensity and/or a viscosity of the medium being measured and which, ingiven cases, can be displayed on-site and/or also sent to a dataprocessing system superordinated to the in-line measuring device, in theform of digital, measured data and there correspondingly furtherprocessed. The above mentioned application of differentially acting,oscillation exciters, or oscillation sensors introduces, among otherthings, also the advantage, that for operating the measuring transducerof the invention, also such established measuring, and operating,electronics can be used, such as have found broad application, forexample, already in conventional Coriolis, mass flow and/or densitymeasuring devices.

The measuring device electronics 12, including the measuring, andoperating, circuit, can, furthermore, be accommodated, for example, in aseparate electronics housing 7 ₂, which is arranged removed from themeasuring transducer or, such as shown in FIG. 1, is affixed directly onthe measuring transducer 1, for example, externally on the transducerhousing 7 ₁, in order to form a single compact device. In the case ofthe here illustrated example of an embodiment, consequently, placed onthe transducer housing 7 ₁ is, additionally, a neck-like, transitionpiece serving for holding the electronics housing 7 ₂. Within thetransition piece can additionally be arranged a feedthrough for theelectrical connecting lines between measuring transducer 11, especiallythe therein placed oscillation exciters and sensors, and the mentionedmeasuring device electronics 12. The feedthrough is manufactured to behermetically sealed and/or pressure resistant, for example, by means ofglass, and/or plastic potting compound.

As already multiply mentioned, the in-line measuring device and, thus,also the measuring transducer 11, is provided, especially, formeasurements also of high mass flows of more than 1000 t/h in a pipelineof large caliber of more than 250 mm. Taking this into consideration,according to an additional embodiment of the invention, the nominaldiameter of the measuring transducer 11, which, as already mentioned,corresponds to a caliber of the pipeline, in whose course the measuringtransducer 11 is to be used, is so selected, that it amounts to morethan 50 mm, especially, however, is greater than 100 mm. Additionally,according to a further embodiment of the measuring transducer, it isprovided, that each of the measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ shows,in each case, a caliber D₁₈ corresponding to a particular tube innerdiameter, which amounts to more than 40 mm. Especially, the measuringtubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ are additionally so embodied, that eachshows a caliber D₁₈ of more than 60 mm. Alternatively thereto or insupplementation thereof, the measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ are,according to another embodiment of the invention, additionally sodimensioned, that they have, in each case, a measuring tube length L₁₈of at least 1000 mm. The measuring tube length L₁₈ corresponds, in thehere illustrated example of an embodiment with equal length measuringtubes 18 ₁, 18 ₂, 18 ₃, 18 ₄, in each case, to a length of a section ofthe deflection curve of the first measuring tube extending between thefirst flow opening of the first flow divider and the first flow openingof the second flow divider. Especially, the measuring tubes 18 ₁, 18 ₂,18 ₃, 18 ₄ are, in such case, so designed, that their measuring tubelength L₁₈ is, in each case, greater than 1200 mm.

Accordingly, there results, at least for the mentioned case, that themeasuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ are composed of steel, in thecase of the usually used wall thicknesses of over 1 mm, a mass of, ineach case, at least 20 kg, especially more than 30 kg. One tries,however, to keep the empty mass of each of the measuring tubes 18 ₁, 18₂, 18 ₃, 18 ₄ smaller than 50 kg.

In consideration of the fact that, as already mentioned, each of themeasuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄, in the case of the measuringtransducer of the invention, weighs well over 20 kg and, in such case,such as directly evident from the above dimensional specifications, canhave a capacity of easily 10 l or more, the tube arrangement comprisingthen the four measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ can, at least inthe case of medium with high density flowing through, reach a total massof far over 80 kg. Especially in the case of the application ofmeasuring tubes with comparatively large caliber D₁₈, large wallthickness and large measuring tube length L₁₈, the mass of the tubearrangement formed by the measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ candirectly, however, also be greater than 100 kg or, at least with mediumflowing through, e.g. oil or water, be more than 120 kg. As a result ofthis, an empty mass M₁₁ of the measuring transducer amounts, in total,also to far more than 200 kg, and, in the case of nominal diameters D₁₁of significantly greater than 250 mm, even more than 300 kg. As aresult, the measuring transducer of the invention can have a mass ratioM₁₁/M₁₈ of an empty mass M₁₁ of the total measuring transducer to anempty mass M₁₈ of the first measuring tube of easily greater than 10,especially greater than 15.

In order, in the case of the mentioned high empty mass M₁₁ of themeasuring transducer, to employ the therefor, in total, applied materialas optimally as possible and, thus, to utilize the—most often also veryexpensive—material, in total, as efficiently as possible, according toan additional embodiment, the nominal diameter D₁₁ of the measuringtransducer is so dimensioned relative to its empty mass M₁₁, that a massto nominal diameter ratio M₁₁/D₁₁ of the measuring transducer 11, asdefined by a ratio of the empty mass M₁₁ of the measuring transducer 11to the nominal diameter D₁₁ of the measuring transducer 11, is smallerthan 2 kg/mm, especially as much as possible, however, smaller than 1kg/mm. In order to assure a sufficiently high stability of the measuringtransducer 11, the mass to nominal diameter ratio M₁₁/D₁₁ of themeasuring transducer 11 is, at least in the case use of the abovementioned conventional materials, however, to be chosen as much aspossible greater than 0.5 kg/mm. Additionally, according to anadditional embodiment of the invention, for additional improvement ofthe efficiency of the installed material, the mentioned mass ratioM₁₁/M₁₈ is kept smaller than 25.

For creation of a nevertheless as compact as possible measuringtransducer of sufficiently high oscillation quality factor and as littlepressure drop as possible, according to an additional embodiment of theinvention, the measuring tubes are so dimensioned relative to the abovementioned, installed length L₁₁ of the measuring transducer 11, that acaliber to installed length ratio D₁₈/L₁₁ of the measuring transducer,as defined by a ratio of the caliber D₁₈ at least of the first measuringtube to the installed length L₁₁ of the measuring transducer 11, amountsto more than 0.02, especially more than 0.05 and/or less than 0.09.Alternatively or in supplementation, the measuring tubes 18 ₁, 18 ₂, 18₃, 18 ₄ are so dimensioned relative to the above mentioned installedlength L₁₁ of the measuring transducer, that a measuring tube length toinstalled length ratio L₁₈/L₁₁ of the measuring transducer, as definedby a ratio of the above-referenced measuring tube length L₁₈ at least ofthe first measuring tube to the installed length L₁₁ of the measuringtransducer, amounts to more than 0.7, especially more than 0.8 and/orless than 0.95.

In case required, possibly or at least potentially, mechanical stressesand/or vibrations caused by the vibrating, especially in the mentionedmanner, relatively large dimensioned, measuring tubes at the inlet sideor at the outlet side in the transducer housing can e.g. be minimized byconnecting the four measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ with oneanother mechanically at least pairwise on the inlet side, and at leastpairwise on the outlet side, in each case, by means of coupling elementsserving as so-called node plates—in the following referred to ascoupling elements of first type. Moreover, by means of such couplingelements of first type, be it through their dimensioning and/or theirpositioning on the measuring tubes, mechanical eigenfrequencies of themeasuring tubes and, thus, also mechanical eigenfrequencies of the tubearrangement formed by means of the four measuring tubes includingthereon placed, additional components of the measuring transducer and,thus, also the oscillatory behavior of the measuring transducer as awhole can, with targeting, be influenced.

The coupling elements of first type serving as node plates can, forexample, be thin plates, or washers, manufactured especially from thesame material as the measuring tubes, which, in each case, correspondingwith the number and the outer dimensions of the measuring tubes to becoupled with one another, are provided with bores, in given cases,supplementally, slitted to the edge, so that the washers can first bemounted onto the respective measuring tubes 18 ₁, 18 ₂, 18 ₃, or 18 ₄and, in given cases, thereafter still be bonded to the respectivemeasuring tubes, for example, by hard soldering or welding.

Accordingly, the tube arrangement comprises, according to an additionalembodiment of the invention, a first coupling element 24 ₁ of firsttype, which is affixed on the inlet side at least to the first measuringtube and to the second measuring tube and spaced both from the firstflow divider as well as also from the second flow divider for forminginlet-side, oscillation nodes at least for vibrations, especiallybending oscillations, of the first measuring tube and for theretoopposite phase vibrations, especially bending oscillations, of thesecond measuring tube, as well as a second coupling element 24 ₂ offirst type, especially a second coupling element 24 ₂ constructedequally to the first coupling element, which is affixed on the outletside at least to the first measuring tube 18 ₁ and to the secondmeasuring tube 18 ₂ and spaced both from the first flow divider 20 ₁ aswell as also from the second flow divider 20 ₂, as well as also from thefirst coupling element 24 ₁, for forming outlet-side, oscillation nodesat least for vibrations, especially bending oscillations, of the firstmeasuring tube 18 ₁ and for thereto opposite phase vibrations,especially bending oscillations, of the second measuring tube 18 ₂. Asdirectly evident amongst others from FIGS. 4 a, 4 b, and FIGS. 5 a, 5 b,respectively, the first coupling element 24 ₁ of first type is affixedon the inlet side also to the third measuring tube 18 ₃ and to thefourth measuring tube 18 ₄ and spaced both from the first flow divider20 ₁ as well as also from the second flow divider 20 ₂, for forminginlet-side, oscillation nodes also for vibrations, especially bendingoscillations, of the third measuring tube 18 ₃ and for thereto oppositephase vibrations, especially bending oscillations, of the fourthmeasuring tube 18 ₄, and the second coupling element 24 ₂ of first typeis affixed on the outlet side also to the third measuring tube 18 ₃ andto the fourth measuring tube 18 ₄ and spaced both from the first flowdivider 20 ₁ as well as also from the second flow divider 20 ₂, as wellas also from the first coupling element 24 ₁, for forming outlet-side,oscillation nodes at least for vibrations, especially bendingoscillations, of the third measuring tube 18 ₃ and for thereto oppositephase vibrations, especially bending oscillations, of the fourthmeasuring tube 18 ₄, so that, as a result, all four measuring tubes 18₁, 18 ₂, 18 ₃, 18 ₄ are mechanically connected with one another by meansof the first coupling element 24 ₁ of first type as well as by means ofthe second coupling element 24 ₂ of first type. Each of the twoaforementioned coupling elements 24 ₁, 24 ₂ of first type, especiallycoupling elements constructed equally to one another, is, according toan additional embodiment of the invention, plate shaped, especially insuch a manner, that it shows, as well as also directly evident from thecombination of figures, a rather rectangular or also square, basic shapeor, however, that it shows, rather, a round, an oval, a cross shaped or,such as, for example, also provided in US-A 2006/0283264, a ratherH-shaped basic shape.

As amongst others directly evident from FIGS. 4 a, 4 b, and FIGS. 5 a, 5b, respectively, the two aforementioned coupling elements 24 ₁, 24 ₂ areadditionally so embodied and so placed in the measuring transducer, thata center of mass of the first coupling element 24 ₁ of first type showsa distance to a center of mass of the measuring transducer 11, which isessentially equal to a distance of a center of mass of the secondcoupling element 24 ₂ of first type to said center of mass of themeasuring transducer 11, especially in such a manner, that the twocoupling elements 24 ₁, 24 ₂ are, as a result, arranged symmetrically toa shared imaginary cross sectional plane, in each case, cuttingcentrally through the measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄.

For additionally increasing the degrees of freedom in the case ofoptimizing the oscillatory behavior of the tube arrangement formed bymeans of the four measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄, the tubearrangement comprises, according to a further development of theinvention, additionally a third coupling element 24 ₃ of first type,which is affixed on the inlet side at least to the third measuring tube18 ₃ and to the fourth measuring tube 18 ₄ and spaced both from thefirst flow divider 20 ₁ as well as also from the second flow divider 20₂ for forming inlet-side, oscillation nodes at least for vibrations,especially bending oscillations, of the third measuring tube 18 ₃ andfor thereto opposite phase vibrations, especially bending oscillations,of the fourth measuring tube 18 ₄. Moreover, the measuring transducer 11comprises, in the case of this further development, a fourth couplingelement 24 ₄ of first type, especially a fourth coupling elementconstructed equally to the third coupling element 24 ₃ of first type,which fourth coupling element is affixed on the outlet side at least tothe third measuring tube 18 ₃ and to the fourth measuring tube 18 ₄ andspaced both from the first flow divider 20 ₁ as well as also from thesecond flow divider 20 ₂, as well as also from the third couplingelement 24 ₃ of first type, for forming outlet-side, oscillation nodesat least for vibrations, especially bending oscillations, of the thirdmeasuring tube 18 ₃ and for thereto opposite phase vibrations,especially bending oscillations, of the fourth measuring tube 18 ₄.

Each of the two aforementioned third and fourth coupling elements 24 ₃,24 ₄ of first type, especially third and fourth coupling elementsconstructed equally to one another, is embodied, according to anadditional embodiment of the invention, again, plate shaped, especiallyin such a manner, that it shows a rectangular, square, round, crossshaped or H-shaped, basic shape.

As shown in FIG. 4 a, and in FIGS. 5 a, 5 b, respectively, the thirdcoupling element 24 ₃ of first type is affixed on the inlet side also tothe first measuring tube 18 ₁ and to the second measuring tube 18 ₂ andspaced both from the first flow divider 20 ₁ as well as also from thesecond flow divider 20 ₂, as well as also from the first couplingelement of first type 24 ₁ and the fourth coupling element 24 ₄ of firsttype is affixed on the outlet side also to the first measuring tube andto the second measuring tube and spaced both from the first flow divideras well as also from the second flow divider, as well as also from thesecond coupling element, so that, as a result, all four measuring tubes18 ₁, 18 ₂, 18 ₃, 18 ₄ are also mechanically connected with one anotherby means of the third coupling element 24 ₃ of first type as well as bymeans of the fourth coupling element 24 ₄ of first type.

As directly evident from the combination of FIGS. 4 a, 4 b, 5 a, 5 b,also the third and fourth coupling elements 24 ₃, 24 ₄ are additionallyso embodied and so placed in the measuring transducer, that a center ofmass of the third coupling element 24 ₃ of first type shows a distanceto the center of mass of the measuring transducer, which essentially isequal to a distance of a center of mass of the fourth coupling element24 ₄ of first type to said center of mass of the measuring transducer,especially in such a manner, that the two coupling elements 24 ₃, 24 ₄are, as a result, arranged symmetrically to a shared imaginary crosssectional plane, in each case, cutting centrally through the fourmeasuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄. Additionally, according to afurther embodiment of the invention, the four coupling element 24 ₁, 24₂, 24 ₃, 24 ₄ of first type are so arranged in the measuring transducer,that the distance of the center of mass of the third coupling element 24₃ of first type from the center of mass of the measuring transducer isgreater than the distance of the center of mass of the first couplingelement 24 ₁ of first type from said center of mass of the measuringtransducer and greater than the distance of the center of mass of thesecond coupling element 24 ₂ of first type from said center of mass ofthe measuring transducer.

As directly evident from the combination of FIGS. 4 a, 4 b, 5 a and 5 b,the tube form of each of the measuring tubes together with a minimumseparation between the coupling element of first type affixed on theinlet side to a particular measuring tube and lying nearest to thecenter of mass of the measuring transducer 11—here thus the firstcoupling element 24 ₁ of first type—, and the coupling element of firsttype affixed on the outlet side to said measuring tube and lying nearestto the center of mass of the measuring transducer—here thus the secondcoupling element 24 ₂ of first type—, define, in each case, a free,oscillatory length, L_(18x), of such measuring tube. The freeoscillatory length, L_(18x), of a respective measuring tube corresponds,in such case, as also schematically presented in FIGS. 5 a and 5 b, to alength of the section the deflection curve the said measuring tubeextending between the coupling elements 24 ₁, 24 ₂, wherein, accordingto an additional embodiment of the invention, the coupling elements offirst type are so placed in the measuring transducer, that, as a result,the free, oscillatory length of each of the measuring tubes 18 ₁, 18 ₂,18 ₃, 18 ₄ amounts to less than 3000 mm, especially less than 2500 mmand/or more than 800 mm. Alternatively or in supplementation, it isadditionally provided, that the measuring tubes are so constructed andthe coupling elements of first type are so arranged, that all fourmeasuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄, as a result, have the same freeoscillatory length, L_(18x). According to an additional embodiment ofthe invention, additionally, the first measuring tube and the secondmeasuring tube are, at least over the region extending between the firstcoupling element of first type and the second coupling element of firsttype—consequently thus their free oscillatory length—parallel to oneanother, and also the third measuring tube and the fourth measuring tubeare, at least over the region extending between the first couplingelement of first type and the second coupling element of firsttype—consequently thus their respective free oscillatory length—parallelto one another

It can additionally, in the context of a still simpler and yet moreexact adjusting of the oscillatory behavior of the measuring transducer,be quite of advantage, when the measuring transducer, such as, forexample, provided in US-A 2006/0150750, moreover, includes still othercoupling elements of the aforementioned type serving for forming inlet,or outlet, side, oscillation nodes for vibrations, especially bendingoscillations, of the first measuring tube and for thereto opposite phasevibrations, especially bending oscillations, of the second measuringtube, or for vibrations, especially bending oscillations, of the thirdmeasuring tube and for thereto opposite phase vibrations, especiallybending oscillations, of the fourth measuring tube, for example, thus,in total, 6 or 8 such coupling elements of first type.

For creation of an as compact as possible measuring transducer ofsufficiently high oscillation quality factor and high sensitivity in thecase of as little pressure drop as possible, according to an additionalembodiment of the invention, the measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄are so dimensioned relative to the mentioned free, oscillatory lengththat a caliber to oscillatory length ratio D₁₈/L_(18x) of the measuringtransducer, as defined by a ratio of the caliber D₁₈ of the firstmeasuring tube to the free, oscillatory length L_(18x) of the firstmeasuring tube, amounts to more than 0.03, especially more than 0.05and/or less than 0.15. Alternatively or in supplementation, for this,according to an additional embodiment of the invention, the measuringtubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ are so dimensioned relative to the abovementioned installed length L₁₁ of the measuring transducer that anoscillatory length to installed length ratio L_(18x)/L₁₁ of themeasuring transducer, as defined by a ratio of the free, oscillatorylength L_(18x) of the first measuring tube to the installed length L₁₁of the measuring transducer, amounts to more than 0.55, especially morethan 0.6 and/or less than 0.9.

According to an additional embodiment of the invention, the oscillationsensors, relative to the free, oscillatory length, are so arranged inthe measuring transducer, that a measuring length to oscillatory lengthratio of the measuring transducer, as defined by a ratio of thementioned measuring length of the measuring transducer to the free,oscillatory length of the first measuring tube, amounts to more than0.3, especially more than 0.4 and/or less than 0.95.

For creation of an as compact as possible measuring transducer, whichis, nevertheless, however, as sensitive as possible to mass flow,according to an additional embodiment of the invention, the oscillationsensors are so arranged in the measuring transducer relative to theinstalled length of the measuring transducer that a measuring length toinstalled length ratio of the measuring transducer, which is defined bya ratio of the measuring length to the installed length of the measuringtransducer, amounts to more than 0.3, especially more than 0.4 and/orless than 0.7. Alternatively or in supplementation, the oscillationsensors are, according to an additional embodiment of the invention, soplaced in the measuring transducer relative to the measuring tubes, thata caliber to measuring length ratio D₁₈/L₁₉ of the measuring transducer,which is defined by a ratio of the caliber D₁₈ of the first measuringtube to the mentioned measuring length L₁₉ of the measuring transducer,amounts to more than 0.05, especially more than 0.09. In an additionalembodiment of the invention, additionally, the above mentioned measuringlength L₁₉ is kept smaller than 1200 mm.

In an additional embodiment of the invention, it is further providedthat the measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ are driven, duringoperation, pairwise synchronously, thus with equal phase position, sothat the oscillations of all four measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄are only pairwise out of phase. In advantageous manner, the oscillatorybehavior of the tube arrangement formed by means of the four measuringtubes 18 ₁, 18 ₂, 18 ₃, 18 ₄, as well as also the driver signalscontrolling the exciter mechanism, are so matched to one another, thatat least the oscillations of the four measuring tubes 18 ₁, 18 ₂, 18 ₃,18 ₄ excited in the wanted mode are so developed, that the first and thesecond measuring tubes 18 ₁, 18 ₂ oscillate with essentially oppositephase relative to one another, thus with an opposing phase shift ofabout 180°, and also the third and fourth measuring tubes 18 ₃, 18 ₄oscillate with essentially opposite phase relative to one another,while, simultaneously, the first and third measuring tubes 18 ₁, 18 ₃oscillate with essentially equal phase relative to one another and thesecond and fourth measuring tubes 18 ₂, 18 ₄ oscillate with essentiallyequal phase relative to one another.

Therefore, the tube arrangement includes, according to a furtherembodiment of the invention, additionally a first coupling element 25 ₁of second type, e.g. a plate shaped, first coupling element 25 ₁ ofsecond type, which is affixed only to the first measuring tube 18 ₁ andto the third measuring tube 18 ₃ and spaced both from the first couplingelement 24 ₁ of first type as well as also from the second couplingelement 24 ₂ of first type, for synchronizing vibrations, especiallybending oscillations, of the first measuring tube 18 ₁ and thereto equalfrequency vibrations, especially bending oscillations, of the thirdmeasuring tube 18 ₃. Furthermore, the tube arrangement comprises, atleast in the case of this embodiment of the invention, at least a secondcoupling element 25 ₂ of second type, e.g. a plate shaped, secondcoupling element 25 ₂ of second type, which is affixed only to thesecond measuring tube 18 ₂ and to the fourth measuring tube 18 ₄ andspaced both from the first coupling element 24 ₁ of first type as wellas also from the second coupling element 24 ₁ of first type, as well asalso from the first coupling element 25 ₁ of second type, forsynchronizing vibrations, especially bending oscillations, of the secondmeasuring tube 18 ₂ and thereto equal frequency vibrations, especiallybending oscillations, of the fourth measuring tube 18 ₄. As directlyevident from the combination of FIGS. 4 a, 4 b, 5 a and 5 b, the firstand second coupling elements 25 ₁, 25 ₂ of second type are placed in themeasuring transducer 11 as oppositely lying to one another as possible.

An advantage of the mechanical coupling of the measuring tubes in theabove described manner is, among other things, to be seen in the factthat the four measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ are reduced to twomeasuring tube composites acting, in each case, effectively as oneoscillatory system, each thus acting essentially as a single measuringtube, since the exciter forces produced by the exciter mechanism 5 act,due to the mechanical coupling, both between the first and secondmeasuring tubes 18 ₁, 18 ₂ as well as also equally between the third andfourth measuring tubes 18 ₃, 18 ₄, and, in turn, also the reactionforces caused in the through-flowing media for purposes of the measuringare transmitted, in each case, together back to the oscillation sensorsof the sensor arrangement 5. Furthermore, possible differences betweenthe individual measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ can as regardstheir nominal oscillatory behavior, e.g. as a result of non-uniformflow, different temperatures, and/or different density distributions,etc., be cancelled in very simple manner. The application of couplingelements of second type has additionally also the advantage, that eachof the two measuring tube composites formed, thus, in very simplemanner, acts, not only for the exciter mechanism, but equally also forthe sensor arrangement 19, and, thus, also for the measuring, andoperating, circuit of the measuring device electronics 12, in total,practically, in each case, as a single measuring tube, and the measuringtransducer 11, thus, from the point of view of the measuring, andoperating, circuit, seems to have only two measuring tubes oscillatingrelative to one another. As a result of this, at least for thepreprocessing and possible digitizing of the oscillation measurementsignals, proven signal processing technologies and also proven,especially two channel (thus processing oscillation measurement signalsdelivered from only two oscillation sensors) measuring circuits from thefield of Coriolis, mass flow, or density measurement, can be utilized.Equally, thus, also for the operating circuit driving the excitermechanism, driver circuits known to those skilled in the art, especiallysuch operating on one channel, thus delivering exactly one driver signalfor the exciter mechanism, can be directly used. In case required,however, also the oscillation measurement signals delivered, in eachcase, from the two or more oscillation sensors can, however, also beindividually preprocessed and correspondingly digitized in, in eachcase, separate measuring channels; equally, in case required, also the,in given cases, present, two or more oscillation exciters can beoperated separately by means of separate driver signals.

In case required—for example, because the measuring transducer is usedfor the measuring extremely hot media, or for measuring in applicationswith operating temperatures fluctuating over a broad region, forinstance, as a result of recurringly in-situ performed, cleaningprocedures for the measuring transducer (“cleaning in process”,“sterilizing in process”) and, thus, mentionable thermal expansions ofthe measuring tubes are to be expected—, the coupling elements secondtype can additionally be so embodied, that they expand essentially thesame as the measuring tubes and/or that they are sufficiently flexible,at least relative to forces, which extend in the direction of a line ofaction extending through the peaks of the two measuring tubes connectedwith one another by the particular coupling elements of second type or aline of action parallel thereto. The latter can be implemented, forexample, by slits formed correspondingly in the particular couplingelement—here, in each case, extending essentially transversely toaforementioned line of action—or, however, also by application of thinplates, or rods as coupling elements of second type. As a result, thereis so also possible a small relative movement of the two measuring tubesconnected by means of the respective coupling elements of second type,whereby the bent measuring tubes can—in case required for the particularapplication—be excited in the wanted mode, in each case, also to typicalbending oscillations in the manner of a terminally clamped cantilever.

According to an embodiment of the invention, the measuring tubes 18 ₁,18 ₂, 18 ₃, 18 ₄, as well as the coupling elements connecting these withone another, are, consequently, additionally so formed and somechanically coupled with one another by means of coupling elements ofsecond type, in given cases, supplementally also by means of couplingelements of first type, that a first measuring tube composite formedfrom the first and the third measuring tubes 18 ₁, 18 ₃ and a secondmeasuring tube composite formed by the second and the fourth measuringtubes 18 ₂, 18 ₄ have essentially the same mechanical eigenfrequencies.

In the example of an embodiment shown here, the first coupling element25 ₁ of second type is affixed to the first and third, measuring tubes18 ₁, 18 ₃, respectively, in the region of 50% of a minimum separationbetween the first coupling element 24 ₁ of first type and the secondcoupling element 24 ₂ of first type—, as a result, thus at about halfthe free, oscillatory length of the first and third measuring tubes 18₁, 18 ₃, respectively. Additionally, also the second coupling element ofsecond type is in corresponding manner affixed to the second and fourthmeasuring tubes 18 ₂, 18 ₄, respectively, in the region of 50% of aminimum separation between the first coupling element 24 ₁ of first typeand the second coupling element 24 ₂ of first type, thus at about halfthe free, oscillatory length of the second and fourth measuring tubes 18₂, 18 ₄, respectively.

In advantageous manner, the coupling elements of second type cansupplementally also serve as holders of components of the excitermechanism 5. Therefore, according to an additional embodiment of theinvention, it is provided, that each of the oscillation exciters 5 ₁, 5₂, especially equally constructed and/or equally heavy oscillationexciters, is held, partially, in each case, on two coupling elements ofsecond type—here, the first and second coupling elements 25 ₁, 25₂—lying opposite to one another. Thus, it can, in very effective and,equally as well, very simple manner, be assured, that the exciter forcegenerated by means of the oscillation exciter 5 ₁ effects at leastpredominantly synchronous, especially also of essentially equal phase toone another, bending oscillations of the first and third measuring tubes18 ₁, 18 ₃, or the second and fourth measuring tubes 18 ₂, 18 ₄. Forexample, in the case of electrodynamic oscillation exciters, thecylindrical coils can be affixed to the first coupling element of secondtype and the, in each case, associated permanent magnet to theoppositely lying, second coupling element of second type. For thementioned case, in which the exciter mechanism 5 includes twooscillation exciters 5 ₁, 5 ₂, especially oscillation exciters asequally heavy as possible, both the first oscillation exciter 5 ₁ aswell as also the second oscillation exciter 5 ₂ can, in each case, beheld on the first and second coupling elements 25 ₁, 25 ₂ of secondtype, for example, also in such a manner, that, as directly evident fromFIG. 4, or FIG. 5 a, there is a minimum separation between the first andsecond oscillation exciters 5 ₁, 5 ₂ of more than three times as largeas a tube outer diameter of the measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄,at least, however, of the first measuring tube 18 ₁, while being kept,in total, as small as possible, in order to enable an optimalexploitation of the available room in the inner space of the transducerhousing 7 ₁, as well as also a simple mounting of the oscillationexciters 5 ₁, 5 ₂. Alternatively to the application of a secondoscillation exciter 5 ₂ held on the first and second coupling elements25 ₁, 25 ₂ of second type or in supplementation thereof, balancingmasses can, as, for example, also shown in the initially mentioned US-A2007/0151368, be placed on the two coupling elements for the purpose ofpreventing of undesired torsional moments, especially such around thelongitudinal axis L.

According to an additional embodiment of the invention, the measuringtransducer comprises, additionally, a third coupling element 25 ₃ ofsecond type, for example, again, a plate shaped or rod shaped, couplingelement of second type, which is affixed only to the first measuringtube 18 ₁ and to the third measuring tube 18 ₃ and spaced both from thefirst coupling element 24 ₁ of first type as well as also from thesecond coupling element 24 ₂ of first type, as well as also from thefirst coupling element 25 ₁ of second type, for synchronizingvibrations, especially bending oscillations, of the first measuring tube18 ₁ and thereto equal frequency vibrations, especially bendingoscillations, of the third measuring tube 18 ₃, as well as a fourthcoupling element 25 ₄ of second type, especially a plate shaped or rodshaped, coupling element of second type, which is affixed only to thesecond measuring tube 18 ₂ and to the fourth measuring tube 18 ₄ andspaced both from the first and second coupling elements of first type aswell as also from the second and third coupling elements of second type,in each case, for synchronizing vibrations, especially bendingoscillations, of the second measuring tube 18 ₂ and thereto equalfrequency vibrations, especially bending oscillations, of the fourthmeasuring tube 18 ₄. The third and fourth coupling elements 25 ₃, 25 ₄of second type are, such as directly evident from the combination ofFIGS. 4 a, 4 b, 5 a, 5 b and 6 a, preferably placed in the measuringtransducer 11 lying opposite to one another.

Additionally, the measuring transducer 11 comprises, according to anadditional embodiment of the invention, a fifth coupling element 25 ₅ ofsecond type, especially a plate shaped or rod shaped fifth couplingelement 25 ₅ of second type, which is affixed only to the firstmeasuring tube 18 ₁ and to the third measuring tube 18 ₃ and spaced bothfrom the first and second coupling elements of first type as well asalso from the first and third coupling elements of second type, forsynchronizing vibrations, especially bending oscillations, of the firstmeasuring tube 18 ₁ and of thereto equal frequency vibrations,especially bending oscillations, of the third measuring tube 18 ₃, aswell as a sixth coupling element 25 ₆ of second type, especially a plateshaped or rod shaped, sixth coupling element 25 ₆ of second type, whichis affixed only to the second measuring tube 18 ₂ and to the fourthmeasuring tube 18 ₄ and spaced, in each case, both from the first andsecond coupling elements of first type as well as also from the second,fourth and fifth coupling elements of second type, for synchronizingvibrations, especially bending oscillations, of the second measuringtube and of thereto equal frequency vibrations, especially bendingoscillations, of the fourth measuring tube. The fifth and sixth couplingelements 25 ₅, 25 ₆ of second type are, preferably, again, placed lyingopposite to one another in the measuring transducer 11.

Furthermore, it can be of advantage to use the aforementioned couplingelements of second type additionally also for holding individualcomponents of the sensor arrangement. In accordance therewith, it isprovided, according to an additional embodiment of the invention, thatthe inlet-side, first oscillation sensor 19 ₁ is held, partially, ineach case, on the third and fourth coupling elements 25 ₃, 25 ₄ ofsecond type. Additionally, the second oscillation sensor 19 ₂ is, incorresponding manner, held on the fifth and sixth coupling elements 25₅, 25 ₆ of second type. Thus, it can, in very effective, equally as wellvery simple manner, be assured, that the oscillation measurement signalgenerated, during operation, by means of the first oscillation sensor 19₁ represents. at least predominantly, synchronous, inlet-side, bendingoscillations (especially also bending oscillations of equal phase to oneanother) of the first and third measuring tubes 18 ₁, 18 ₃ relative tothe equally synchronized, inlet-side, bending oscillations (especiallyalso bending oscillations of phase equal to one another) of the secondand fourth measuring tubes 18 ₂, 18 ₄, or that the oscillationmeasurement signal generated, during operation, by means of the secondoscillation sensor 19 ₂ represents, at least predominantly, synchronous,outlet-side, bending oscillations (especially also bending oscillationsof phase equal to one another) of the first and third measuring tubes 18₁, 18 ₃ relative to the equally synchronized, outlet-side, bendingoscillations (especially also bending oscillations of phase equal to oneanother) of the second and fourth measuring tubes 18 ₂, 18 ₄. Forexample, in the case of electrodynamic oscillation sensors, thecylindrical coil of the first oscillation sensor 19 ₁ can be affixed tothe third coupling element of second type and the associated permanentmagnet to the oppositely lying, fourth coupling element of second type,or the cylindrical coil of the second oscillation sensor 19 ₂ can beaffixed to the fifth, and the associated permanent magnet to theoppositely lying, sixth coupling element of second type. For thementioned case, in which the sensor arrangement 19 is formed by means offour oscillation sensors 19 ₁, 19 ₂, 19 ₃, 19 ₄, according to anadditional embodiment of the invention, both the first oscillationsensor 19 ₁ as well as also the third oscillation sensor 19 ₃ are, ineach case, partially held on the third and fourth coupling elements ofsecond type, especially in such a manner, that, such as directly evidentfrom the combination of FIGS. 4 a, 4 b, 5 a and 5 b, a minimumseparation between the first and third oscillation sensors 19 ₁, 19 ₃ ismore than twice, especially more then 2.5 times, as large as a tubeouter diameter of the first measuring tube 18 ₁. In correspondingmanner, additionally, also the second oscillation sensor 19 ₂ and thefourth oscillation sensor 19 ₄ can, in each case, be held on the fifthand sixth coupling elements of second type. Alternatively to theapplication of third and fourth oscillation sensors held on couplingelements 25 ₁, 25 ₂ of second type or in supplementation thereto,balancing masses can, as, for example, also shown in the initiallymentioned US-A 2007/0151368, be placed on the respective couplingelements for the purpose of preventing of undesired torsional moments,especially such around the longitudinal axis L.

For additional improving of the oscillation quality factor of the tubearrangement in the case of an as short as possible installed length L₁₁of the measuring transducer 11, or in the case of an as short aspossible free oscillatory length L_(18x) of the measuring tubes 18 ₁, 18₂, 18 ₃, or 18 ₄, additionally, annular stiffening elements can be usedon the measuring tubes, of which each is so placed on exactly one of themeasuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄, that it grips around such alongone of its, especially circular orbiting, imaginary peripheral lines;compare, for this, also the initially mentioned U.S. Pat. No. 6,920,798.Especially, it can, in such case, be of advantage, when on each of themeasuring tubes 18 ₁, 18 ₂, 18 ₃, or 18 ₄, at least four such stiffeningelements, especially equally constructed stiffening elements, areplaced. The stiffening elements can, in such case, for example, be soplaced in the measuring transducer 11, that two adjoining stiffeningelements mounted on the same measuring tube have a separation from oneanother, which amounts to at least 70% of a pipe outer-diameter of saidmeasuring tube, at most, however, 150% of such pipe outer-diameter.Proved as especially suitable has been, in such case, a separation fromone another of neighboring stiffening elements lying in the range of 80%to 120% of the pipe-outer diameter of the respective measuring tube 18₁, 18 ₂, 18 ₃, or 18 ₄.

Through the application of four instead of, such as to this point, twomeasuring tubes flowed-through in parallel, it is then also possible tomanufacture, cost effectively, measuring transducers of the describedtype also for large mass flow rates, or with large nominal diameters offar over 250 mm, on the one hand, with an accuracy of measurement ofover 99.8% at an acceptable pressure drop, especially of about 1 bar orless, and, on the other hand, to keep the installed mass, as well asalso the empty mass, of such measuring transducers sufficiently inlimits, that, in spite of large nominal diameter, manufacture,transport, installation, as well as also operation can always stilloccur economically sensibly. Especially also through implementing ofabove explained measures for further developing theinvention—individually or also in combination—, measuring transducers ofthe type being discussed can also, in the case of large nominaldiameter, be so embodied and so dimensioned, that a mass ratio of themeasuring transducer, as defined by a ratio of the mentioned empty massof the measuring transducer to a total mass of the tube arrangement canbe kept directly smaller than 3, especially smaller than 2.5.

While the invention has been illustrated and described in detail in thedrawings and forgoing description, such illustration and description isto be considered as exemplary not restrictive in character, it beingunderstood that only exemplary embodiments have been shown and describedand that all changes and modifications that come within the spirit andscope of the invention as described herein are desired to protected.

What is claimed is:
 1. A measuring transducer of a vibration-type forregistering at least one physical, measured variable of a flowablemedium guided in a pipeline and/or for producing Coriolis forces servingfor registering a mass flow rate of a flowable medium guided in apipeline, said measuring transducer comprising: a transducer housing, ofwhich an inlet-side, first housing end is formed by means of aninlet-side, first flow divider including four, mutually spaced, flowopenings, and an outlet-side, second housing end formed by means of anoutlet-side, second flow divider including four, mutually spaced, flowopenings; a tube arrangement including four curved measuring tubesconnected to said first and second flow dividers, of which a firstmeasuring tube of said four curved measuring tubes opens with aninlet-side, first measuring tube end into a first flow opening of saidfirst flow divider and with an outlet-side, second measuring tube endinto a first flow opening of said second flow divider, a secondmeasuring tube of said four curved measuring tubes, which is at leastsectionally parallel to said first measuring tube, opens with aninlet-side, first measuring tube end into a second flow opening of saidfirst flow divider and with an outlet-side, second measuring tube endinto a second flow opening of said second flow divider, a thirdmeasuring tube of said four curved measuring tubes opens with aninlet-side, first measuring tube end into a third flow opening of saidfirst flow divider and with an outlet-side, second measuring tube endinto a third flow opening of said second flow divider, and a fourthmeasuring tube of said four curved measuring tubes, which is at leastsectionally parallel to the third measuring tube, opens with aninlet-side, first measuring tube end into a fourth flow opening of saidfirst flow divider and with an outlet-side, second measuring tube endinto a fourth flow opening of said second flow divider; and anelectromechanical exciter mechanism for producing and/or maintainingmechanical oscillations of said four curved measuring tubes; whereinsaid four curved measuring tubes are so embodied and arranged in themeasuring transducer, that: said tube arrangement defines a firstimaginary longitudinal-section plane with respect to which said tubearrangement is mirror symmetric, said first imaginarylongitudinal-section plane lying between said first measuring tube andsaid third measuring tube as well as between said second measuring tubeand said fourth measuring tube; and said tube arrangement definesperpendicular to its imaginary first longitudinal-section plane a secondimaginary longitudinal-section plane, with respect to which said tubearrangement likewise is mirror symmetric, said second imaginarylongitudinal-section plane extending between said first measuring tubeand said second measuring tube as well as between said third measuringtube and said fourth measuring tube.
 2. The measuring transducer asclaimed in claim 1, wherein: said two flow dividers are so embodied andarranged in the measuring transducer, that an imaginary first connectingaxis of the measuring transducer imaginarily connecting said first flowopening of said first flow divider with said first flow opening of saidsecond flow divider extends parallel to an imaginary second connectingaxis of the measuring transducer imaginarily connecting said second flowopening of said first flow divider with said second flow opening of saidsecond flow divider, and an imaginary third connecting axis of themeasuring transducer imaginarily connecting said third flow opening ofsaid first flow divider with said third flow opening of said second flowdivider extends parallel to an imaginary fourth connecting axis of saidmeasuring transducer imaginarily connecting said fourth flow opening ofsaid first flow divider with said fourth flow opening of said secondflow divider.
 3. The measuring transducer as claimed in claim 2,wherein: said two flow dividers are so embodied and arranged in themeasuring transducer, that a first imaginary longitudinal-section planeof the measuring transducer, within which said first imaginaryconnecting axis and said second imaginary connecting axis extend, isparallel to a second imaginary longitudinal-section plane of themeasuring transducer, within which said imaginary third connecting axisand said imaginary fourth connecting axis extend.
 4. The measuringtransducer as claimed in claim 3, wherein: said two flow dividers are soembodied and arranged in the measuring transducer in such a manner, thatsaid first imaginary longitudinal-section plane of the tube arrangementlies between said first and second imaginary longitudinal-section planesof the measuring transducer and/or is parallel to the first and secondimaginary longitudinal-section planes of the measuring transducer;and/or said two flow dividers are so embodied and arranged in themeasuring transducer, that a third imaginary longitudinal-section planeof the measuring transducer, within which said imaginary firstconnecting axis and said imaginary third connecting axis extend, isparallel to a fourth imaginary longitudinal-section plane of themeasuring transducer, within which said imaginary second connecting axisand said imaginary fourth connecting axis extend; and/or said two flowdividers are so embodied and arranged in the measuring transducer, thatsaid first and second connecting axes are parallel to a principal flowaxis of the measuring transducer aligning with the pipeline.
 5. Themeasuring transducer as claimed in claim 3, wherein: said two flowdividers are so embodied and arranged in the measuring transducer insuch a manner, that said first imaginary longitudinal-section plane ofthe tube arrangement lies between said first and second imaginarylongitudinal-section planes of the measuring transducer and/or isparallel to said first and second imaginary longitudinal-section planesof the measuring transducer; and that a third imaginarylongitudinal-section plane of the measuring transducer, within whichsaid imaginary first connecting axis and said imaginary third connectingaxis extend, is parallel to a fourth imaginary longitudinal-sectionplane of the measuring transducer, within which said imaginary secondconnecting axis and said imaginary fourth connecting axis extend.
 6. Themeasuring transducer as claimed in claim 5, wherein: said measuringtubes are so embodied and arranged in the measuring transducer, thatsaid second imaginary longitudinal-section plane of the tube arrangementextends between said third imaginary longitudinal-section plane of themeasuring transducer and said fourth imaginary longitudinal-sectionplane of the measuring transducer.
 7. The measuring transducer asclaimed in claim 6, wherein: said measuring tubes are embodied andarranged in the measuring transducer in such a manner, that said secondimaginary longitudinal-section plane of the tube arrangement is parallelto said third imaginary longitudinal-section plane of the measuringtransducer and parallel to said fourth imaginary longitudinal-sectionplane of the measuring transducer.
 8. The measuring transducer asclaimed in claim 1, further comprising: a first coupling element of afirst type which is affixed on the inlet side at least to said firstmeasuring tube and to said second measuring tube and spaced both fromsaid first flow divider as well as also from said second flow divider,for forming inlet-side, oscillation nodes at least for vibrations ofsaid first measuring tube and for thereto opposite phase vibrations ofsaid second measuring tube; as well as a second coupling element of afirst type, which is affixed on the outlet side at least to said firstmeasuring tube and to said second measuring tube and spaced both fromsaid first flow divider as well as also from said second flow divider,as well as also from said first coupling element, for formingoutlet-side, oscillation nodes at least for vibrations of said firstmeasuring tube and for thereto opposite phase vibrations of said secondmeasuring tube.
 9. The measuring transducer as claimed in claim 8,wherein: said first flow divider includes a flange for connecting themeasuring transducer to a tubular segment of the pipeline serving forsupplying medium to the measuring transducer and said second flowdivider includes a flange for connecting the measuring transducer to atubular segment of the pipeline serving for removing medium from themeasuring transducer, each of said flanges including, respectively, asealing surface for fluid tight connecting of the measuring transducerwith a corresponding tubular segment of the pipeline, and a distancebetween the sealing surfaces of both flanges defines an installedlength, L₁₁, of the measuring transducer; and an oscillatory length toinstalled length ratio, L_(18x)/L₁₁, of the measuring transducer, asdefined by a ratio of the free, oscillatory length, L_(18x), of saidfirst measuring tube, corresponding to a free, oscillatory length,L_(18x), of said first measuring tube corresponding to a length of asection of the deflection curve extending between said first couplingelement of a first type and said second coupling element of a firsttype, to the installed length, L₁₁, of the measuring transducer, amountsto more than 0.55.
 10. The measuring transducer as claimed in claim 8,wherein: a free, oscillatory length, L_(18x), of said first measuringtube corresponding to a length of a section of the deflection curveextending between said first coupling element of a first type and saidsecond coupling element of a first type, amounts to more than 800 mm;and/or said first measuring tube and said second measuring tube areparallel to one another at least over a region extending between saidfirst coupling element of a first type and said second coupling elementof a first type; and third measuring tube and said fourth measuring tubeare parallel to one another at least over a region extending betweensaid first coupling element of a first type and said second couplingelement of a first type.
 11. The measuring transducer as claimed inclaim 10, wherein: a caliber to oscillatory length ratio, D₁₈/L_(18x),of the measuring transducer, as defined by a ratio of a caliber, D₁₈, ofsaid first measuring tube to the free, oscillatory length, L_(18x), ofsaid first measuring tube, amounts to more than 0.03.
 12. The measuringtransducer as claimed in claim 1, wherein: each of the four measuringtubes shows a caliber, D₁₈, which amounts to more than 40 mm; and/orsaid measuring tubes are so curved and so arranged, that a caliber toheight ratio of the tube arrangement, defined by a ratio of a caliber,D₁₈, of said first measuring tube to a maximal lateral expanse of thetube arrangement, measured from a peak of said first measuring tube to apeak of said third measuring tube, amounts to more than 0.1; and/or ameasuring tube length, L₁₈, of said first measuring tube correspondingto a length of a section, extending between the first flow opening ofsaid first flow divider and the first flow opening of said second flowdivider, of a deflection curve of said first measuring tube amounts tomore than 1000 mm.
 13. The measuring transducer as claimed in claim 1,wherein: said first flow divider includes a flange for connecting themeasuring transducer to a tubular segment of the pipeline serving forsupplying medium to the measuring transducer; and said second flowdivider includes a flange for connecting the measuring transducer to atubular segment of the pipeline serving for removing medium from themeasuring transducer.
 14. The measuring transducer as claimed in claim13, wherein: each of the flanges includes, respectively, a sealingsurface for fluid tight connecting of the measuring transducer with acorresponding tubular segment of the pipeline, and a distance betweenthe sealing surfaces of both flanges defines an installed length, L₁₁,of the measuring transducer.
 15. The measuring transducer as claimed inclaim 14, wherein: the installed length amounts to more than 1200 mm; ameasuring tube length to installed length ratio, L₁₈/L₁₁, of themeasuring transducer, as defined by a ratio of a measuring tube length,L₁₈, of said first measuring tube to the installed length, L₁₁, of themeasuring transducer, amounts to more than 0.7, said measuring tubelength, L₁₈, corresponding to a length of a section, extending betweenthe first flow opening of said first flow divider and the first flowopening of said second flow divider, of a deflection curve of the firstmeasuring tube; and/or a caliber to installed length ratio, D₁₈/L₁₁, ofthe measuring transducer, as defined by a ratio of a caliber, D₁₈, ofsaid first measuring tube to the installed length, L₁₁, of the measuringtransducer, amounts to more than 0.02; and/or a nominal diameter toinstalled length ratio, D₁₁/L₁₁, of the measuring transducer, as definedby a ratio of the nominal diameter of the measuring transducer, whichdiameter corresponds to a caliber of the pipeline, in whose course themeasuring transducer is to be used, to the installed length of themeasuring transducer, is smaller than 0.3; and/or the sensor arrangementincludes an inlet-side, first oscillation sensor, an outlet-side, secondoscillation sensor, an inlet-side, third oscillation sensor, and afourth oscillation sensor, and a measuring length to oscillatory lengthratio, L₁₉/L_(18x), of the measuring transducer, as defined by a ratioof a measuring length, L₁₉, of the measuring transducer corresponding toa length of a section of a deflection curve of said first measuring tubeextending between said first oscillation sensor and said secondoscillation sensor to the free, oscillatory length, L_(18x), of thefirst measuring tube, amounts to more than 0.3.
 16. The measuringtransducer as claimed in claim 1, further comprising: a sensorarrangement reacting to vibrations of said measuring tubes for producingoscillation measurement signals representing vibrations of saidmeasuring tubes.
 17. The measuring transducer as claimed in claim 16,wherein: said sensor arrangement includes an inlet-side, firstoscillation sensor, an outlet-side, second oscillation sensor, aninlet-side, third oscillation sensor, and a fourth oscillation sensor.18. The measuring transducer as claimed in claim 17, wherein: said firstand third oscillation sensors are interconnected electrically in series,in such a manner, that a combined oscillation measurement signalrepresents combined inlet-side oscillations of said first and thirdmeasuring tubes relative to said second and fourth measuring tubes; andsaid second and fourth oscillation sensors are interconnectedelectrically in series, in such a manner, that a combined oscillationmeasurement signal represents combined outlet-side oscillations of saidfirst and third measuring tubes relative to said second and fourthmeasuring tubes.
 19. The measuring transducer as claimed in claim 17,wherein: a measuring length, L₁₉, of the measuring transducercorresponding to a length of a section of a deflection curve of saidfirst measuring tube extending between said first oscillation sensor andsaid second oscillation sensor amounts to more than 500 mm; and/or ameasuring length to installed length ratio, L₁₉/L₁₁, of the measuringtransducer, as defined by a ratio of a measuring length, L₁₉,corresponding to a length of a section of a deflection curve of saidfirst measuring tube extending between said first oscillation sensor andsaid second oscillation sensor, to the installed length, L₁₁, of themeasuring transducer, amounts to more than 0.3; and/or a caliber tomeasuring length ratio, D₁₈/L₁₉, of the measuring transducer, as definedby a ratio of a caliber, D₁₈, of said first measuring tube to ameasuring length, L₁₉, of the measuring transducer corresponding to alength of a section of a deflection curve of said first measuring tubeextending between said first oscillation sensor and said secondoscillation sensor, amounts to more than 0.05.
 20. The measuringtransducer as claimed in claim 1, wherein: a mass ratio, M₁₁/M₁₈, of anempty mass, M₁₁, of the total measuring transducer to an empty mass,M₁₈, of said first measuring tube is greater than 10; and/or each ofsaid two flow dividers shows a mass of more than 20 kg; and/or an emptymass, M₁₈, of said first measuring tube is greater than 20 kg; and/or anempty mass, M₁₁, of the measuring transducer is greater than 200 kg;and/or a nominal diameter, D₁₁, of the measuring transducer, whichcorresponds to a caliber of the pipeline, in whose course the measuringtransducer is to be used, amounts to more than 50 mm; and/or a mass tonominal diameter ratio, M₁₁/D₁₁, of the measuring transducer, as definedby a ratio of an empty mass, M₁₁, of the measuring transducer to thenominal diameter, D₁₁, of the measuring transducer, which diametercorresponds to a caliber of the pipeline, in whose course the measuringtransducer is to be used, is smaller than 2 kg/mm.
 21. The measuringtransducer as claimed in claim 1, wherein: said four measuring tubes areof equal construction as regards a material, of which their tube wallsare composed, and/or as regards their geometric tube dimensions,especially a measuring tube length, a tube wall thickness, a tube outerdiameter and/or a caliber; and/or a material, of which the tube walls ofsaid four measuring tubes are at least partially composed, is titaniumand/or zirconium and/or duplex steel and/or super duplex steel.
 22. Themeasuring transducer as claimed in claim 1, wherein: said transducerhousing, said flow dividers and tube walls of said measuring tubes arecomposed, in each case, of steel, especially stainless steel.
 23. Themeasuring transducer as claimed in claim 1, wherein: each of saidmeasuring tubes shows a bending oscillation fundamental mode of minimumbending oscillation, resonance frequency, f₁₈₁; f₁₈₂; f₁₈₃; f₁₈₄, withthe minimum bending oscillation, resonance frequencies, f₁₈₁, f₁₈₂, atleast of said first and second measuring tubes are essentially equal andthe minimum bending oscillation, resonance frequencies, f₁₈₃, f₁₈₄, atleast of said third and fourth measuring tubes are essentially equal.24. The measuring transducer as claimed in claim 1, wherein: said fourflow openings of said first flow divider are so arranged, that imaginaryarea centers of gravity associated with the cross sectional areas ofsaid four flow openings of said first flow divider form the vertices ofan imaginary square, said cross sectional areas lying in a sharedimaginary cross sectional cutting plane of said first flow divider; andthe four flow openings of the second flow divider are so arranged, thatimaginary areal centers of gravity associated with cross sectional areasof the flow openings of the second flow divider form the vertices of animaginary square, said cross sectional areas lying in a shared imaginarycross sectional cutting plane of the second flow divider.
 25. Themeasuring transducer as claimed in claim 1, wherein: said excitermechanism is embodied in such a manner that said first measuring tubeand said second measuring tube are excitable during operation toopposite phase, bending oscillations and said third measuring tube andsaid fourth measuring tube are excitable during operation to oppositephase bending oscillations; and/or said exciter mechanism is formed bymeans of a first oscillation exciter differentially excitingoscillations of said first measuring tube relative to said secondmeasuring tube, and by means of a second oscillation exciterdifferentially exciting oscillations of said third measuring tuberelative to said fourth measuring tube.
 26. The measuring transducer asclaimed in claim 1, wherein: a middle segment of said transducer housingis formed by means of a straight tube.
 27. The measuring transducer asclaimed in claim 1, wherein: not more than four curved measuring tubesare provided.
 28. The measuring transducer as claimed in claim 1,wherein: said four curved measuring tubes are aligned only pairwiseparallel.
 29. An in-line measuring device for measuring a density and/ora mass flow rate, totaled over a time interval, of a medium, which canbe one of: a gas, a liquid, a powder or other flowable material, flowingin a pipeline, at least at times, with a mass flow rate of more than1000 t/h, which in-line measuring device, embodied as a compact device,comprises: a measuring transducer as claimed in claim 1; as well asmeasuring device electronics electrically coupled with said measuringtransducer, and mechanically rigidly connected with said measuringtransducer.
 30. The use of a measuring transducer according to claim 1for measuring a density and/or a mass flow rate, totaled over a timeinterval, of a medium, which can be one of: a gas, a liquid, a powder orother flowable material, flowing in a pipeline, at least at times, witha mass flow rate of more than 1000 t/h, and in particular more than 1500t/h.